Free-ranging rhinoceros populations are currently threatened due to habitat loss and poaching, and populations under managed care are not self-sustaining. Understanding theriogenology, the study of reproductive medicine, is important if these animals are to be managed effectively to create insurance populations against ecologically or anthropomorphically induced population declines. While there have been many studies evaluating the reproductive physiology and pathology of rhinoceros, there is still a lack of understanding regarding what is considered normal during birth and early calf development. By using video recordings and written medical records, we described the expected timelines for the phases of birth and calf development, as well as the frequency of anterior versus posterior calf positioning during birth and the prevalence of stillbirth. Equine parameters were used as a model for comparison for the results from this study due to the close taxonomic relationship between horses and rhinoceros. The results from this study will help guide clinical decisions for veterinary intervention during and after birth to achieve the best success for the health of the dam and the calf. Establishing references for birth and calf development will aid in sustaining populations of these endangered species in captivity, thereby creating a long-standing impact on the conservation of all rhinoceros species.Diceros bicornis), n = 4; greater one-horned rhinoceros (GOHR) (Rhinoceros unicornis), n = 21; and southern white rhinoceros (SWR) (Ceratotherium simum simum), n = 22) managed under human care in the United States. Using equine parameters as a model for comparison, we compiled the following data: the signs of impending parturition, durations of the parturition phases, calving presentation, frequency of dystocia or stillbirth, and time from birth to neonatal landmarks. Data from 47 births, including 26 videos, were examined. The durations of parturition phases I, II, and III had median lengths of 153 min (n = 18), 28 min (n = 21), and 205 min (n = 15), respectively. Anterior presentation of the calf was observed in 59% births, whereas posterior presentation occurred in 41% births. Posterior calving presentation was associated with a longer phase II of parturition (p = 0.04), although more data are needed to determine whether the posterior presentation of the calf carries a higher risk for stillbirth. Most (83%) stillbirths occurred in GOHR, indicating that this species might be at a higher risk for stillbirth compared to SWR (17%) (p = 0.07). The median time from birth to the calf standing was longer in the GOHR (64 min) compared to the SWR (30 min) (p = 0.02). Detailed descriptions of the parturition parameters and neonatal landmarks in rhinoceros will aid facilities with rhinoceros breeding programs to recognize abnormalities in the parturient or post-partum periods and guide indications for veterinary intervention.Rhinoceros species range from near threatened to critically endangered due to habitat loss and poaching. A sustainable ex situ breeding population is critically important to maintain genetic diversity and help ensure the survival of the species; however, not all populations under human care are self-sustaining. While rhinoceros reproductive physiology and pathology have been well studied, there is still a paucity of information describing the normal parameters of parturition and neonatal landmarks. Using video recordings, medical records, and keeper logs, we reviewed and compared data regarding the parturition of three rhinoceros species (black rhinoceros (BR) ( Ceratotherium simum simum) females under managed care had reproduced successfully, with even lower success amongst rhinoceros that were born under human care versus those that were born in the wild [Free-ranging rhinoceros populations range from near threatened to critically endangered due to habitat loss and illegal trapping or hunting , and popthe wild . Ex situthe wild ; howeverthe wild ; therefoReported causes for the decreased birth rates of rhinoceros managed under human care are primarily associated with factors that occur prior to birth. Examples include altered ovarian cycling and breeding behavior due to small herd compositions ,5, the dThe current knowledge of rhinoceros theriogenology primarily involves the reproductive physiology and pathology ,25,26,27Diceros bicornis), greater one-horned or Indian rhinoceros (Rhinoceros unicornis), and southern white rhinoceros (Ceratotherium simum simum). All animals included in the study were managed under human care in the United States. The primary objective of this study was to establish a set of references regarding rhinoceros pregnancy, birth, and neonatal development. Equine parameters were used as a model for comparison due to the close taxonomic relationship between horses and rhinoceros. The secondary objective was to determine whether there is a significant correlation between the calving presentation and the risk for dystocia or stillbirth. The results from this project are intended to help guide clinical decisions regarding indications for veterinary intervention during the parturient and post-partum periods to achieve the best success for the health of the dam and the calf.In this study, videos, medical records, and keeper logs regarding parturition events in the following species were evaluated: black rhinoceros , greater one-horned rhinoceros (GOHR), and black rhinoceros (BR). In total, documentation of 47 births consisting of videos (n = 26), written records (n = 35), or both were collected. These births occurred between the years 1995 and 2021. SWR (n = 22) and GOHR (n = 21) are equally distributed and well represented within this study, whereas only a small number of BR (n = 4) have been included thus far. All study animals are part of the ex situ population in the United States, representing 8 different zoological institutions.Rhinoceros sondaicus) and Sumatran rhinoceros (Dicerorhinus sumatrensis) were not included in this study, as neither of these species are currently housed in the United States.Inclusion criteria for this study included female primiparous or multiparous rhinoceros of the species previously mentioned and their live or stillborn calves when applicable. Basic identifying information was collected on the sire when available. Javan rhinoceros , medians, minimums, and maximums. In the analysis, 7 of 35 rhinoceros dams had multiple parturitions, for a total of 47 parturition events. Each parturition was considered an independent event. The observed frequencies of the calf presentation, calf position, calf posture, dystocia, assisted delivery, stillbirth, retained placenta, dam position during labor, and sex of the calf were compared between the GOHR and SWR by using a chi-square test. In addition, the gestation length (days), parturition phase I duration (minutes), phase II duration, and phase III duration, and calf time to sternal (minutes), nursing, and urination were compared between the GOHR and SWR by using the non-parametric Wilcoxon Rank Sum test. Black rhinoceros were not included in these comparisons due the small sample size. Finally, the durations of parturition phase I, phase II, and phase III (minutes) were compared between calves with anterior and posterior presentation by using the Wilcoxon Rank Sum test. Study animals with missing data were excluded from the selected statistical comparisons. In all analyses, values of When available, certain late-gestation anatomical changes were evaluated, such as udder development, vulvar edema, and the leaking of milk. Udder development was first noted across the species at a median duration of 21 days prior to birth; however, in some cases, it was first seen up to 2 months prior to parturition . Vulvar edema and the loosening of the tail head and peri-vulvar muscles were noted at a median duration of 19 days prior to parturition . Milk leakage from the udder was first noted at a median duration of 1.5 days prior to birth; however, in one case, milk was reported leaking from the udder 11 days prior to parturition in a SWR .More immediate signs of impending parturition associated with phase I of labor were included in 19 birthing events in this study. Impending signs of labor in the rhinoceros included restlessness, vocalizing, agitation/aggression, horn pressing or rubbing, tail flagging or curling, hind-end rubbing or pressing, kicking out with the hindlimbs, frequent defecation or urination, pawing, anorexia, isolating behavior, and rolling or abdominal stretching. The most reported sign was restlessness , which is characterized by frequent changes of posture between standing and recumbency, as well as by the pacing of the enclosure. The next most reported signs were tail flagging/curling , followed by the rubbing or pressing of the hind end on the walls or bars of the enclosure . Aggressive or agitated behavior  and frequent urination or defecation  were also noted with some frequency .p < 0.01). The shortest gestation was associated with a BR (454 days); however, due to only one data point (n = 1), no significant comparisons could be made to the other species  compared to GOHR gestation (median: 482 days) , 145 min in the GOHR (n = 8), and 197 min in the SWR (n = 9). There was no statistical difference in the length of phase I between the SWR and GOHR. No comparison between species was made with BR, as only one data point was obtained; however, the duration of phase I in this rhinoceros was similar to what was seen in other species, with a length of 118 min (n = 1).Phase II amongst the BR, GOHR, and SWR lasted between 5 and 200 min, with medians of 28 min across all species (n = 21), 63 min in the BR (n = 2), 31 min in the GOHR (n = 9), and 20 min in the SWR (n = 10) . Most daPhase III amongst the BR, GOHR, and SWR lasted between 30 and 343 min, with medians of 205 min across all species (n = 15), 119 min in the GOHR (n = 6), 219 min in the SWR (n = 8), and one data point of 330 min for a BR. There was no statistical difference in the length of phase III between the SWR and GOHR . Again, The anterior presentation of the calf, where the head and forelimbs exit the birth canal first, occurred in 59% of all the rhinoceros births included in this study (17/29). When evaluated by species, anterior presentation was seen in 64% of the GOHR births (7/11) and in 60% of the SWR births (9/15). A total of 33% of the BR births were anterior presentation (1/3); however, this dataset includes only three births in total.The dorsosacral position, in which the dorsal aspect of the calf faces the sacrum of the dam, was seen in 96% (25/26) of the births. The single delivery with abnormal positioning was a GOHR calf that was rotated laterally to a dorsosacral-iliac position while in posterior presentation. This position was associated with one of the two reported dystocias in our study, both of which occurred in GOHR dams . All calves in the study displayed normal postures with the head, neck, and forelimbs or hindlimbs extended depending on anterior or posterior presentation . No births in this study required manual assistance during delivery. No statistical differences were noted in the calf presentation, position, or posture between the SWR and GOHR .p = 0.37). However, phase II of parturition was significantly longer in calves with a posterior presentation  compared to those with an anterior presentation  (p = 0.04). Among the GOHR births specifically, phase II was notably longer in calves with a posterior presentation  compared to those with an anterior presentation  (p = 0.04). Phase III of parturition tended to be longer in calves with a posterior presentation  compared to those with an anterior presentation , but the difference was not statistically significant (p = 0.31)  compared to those with an anterior presentation , but the difference was not statistically significant ( = 0.31) .Male calves occurred in 63% of births where the sex of the calf was known across all species (n = 32). Male calves also occurred more commonly within the species  .p = 0.07). Amongst the GOHR births, 24% (5/21) of the births were stillborn, whereas only 5% (1/22) of the SWR births were stillborn. No stillbirths from BR were included in this study, likely due to the small sample size (Stillbirths were seen in 13% (6/46) of births where the calf viability was known. When comparing between species, the GOHR had more stillbirths  compared to the SWR , although the difference was not statistically significant (ple size .Two of the five stillbirths (40%) amongst the GOHR births were associated with posterior presentation. Both of these stillbirths occurred with the same dam. The first posteriorly presented stillbirth was associated with dystocia, whereas the second stillbirth occurred from an uncomplicated delivery. The calf presentation amongst the other three GOHR stillbirths and the one stillborn event in the SWR was unknown. The clinical significance of the posterior presentation of the calf and increased risk of stillbirth are currently difficult to determine due to the small sample. The data suggest an over-representation of GOHR amongst the stillbirths; however, more data are needed to validate this finding.Dystocia was seen in 6% (2/35) of births where parturition was observed . Two of p = 0.04, p = 0.02). Calves were first noted to be successfully nursing between 65 and 450 min, with a median time of 127 min (n = 15). No statistical difference was noted when comparing the time to nursing between species. The time of first urination was only documented in two calves, one GOHR and one SWR, which occurred 193 and 389 min after birth, respectively. The passage of meconium was described in the medical records from a total of four animals. This occurred anywhere from 26.5 h to 72 h after birth . Time to standing occurred between 20 and 195 min after birth, with a median time of 52 min (n = 19). When comparing the GOHR and SWR calves, the calf times to sternal and standing were shorter in the SWR calves compared to the GOHR calves  and standing (195 min) in this study were associated with this calf. The birth occurred inside in a boma bedded with straw and the calf presented in posterior presentation, but the birth was considered uncomplicated. This calf was born with a valgus malformation of the right hind foot that later self-resolved.This is the first study in the United States to evaluate and report rhinoceros parturition events as well neonatal landmarks from data acquired through a video recording database. Additionally, this is the first report of its kind to include GOHR and BR. It is important to note that the submission of the rhino parturition information and videos was voluntary; therefore, our dataset is not comprehensive. Our primary focus of analysis was aimed towards describing the signs of impending parturition, determining the lengths of the three phases of parturition, identifying normal fetal presentations during birth, and establishing an expected timeline of neonatal development, such as the time to standing and nursing. These established guidelines will help rhinoceros breeding facilities and veterinarians to know what to expect and, consequently, when to intervene.Late-gestation anatomical changes, such as udder development and vulvar edema, are useful tools to give caretakers an indication of impending parturition. This can be especially helpful when the date of breeding is unknown and, therefore, the expected due date for the dam falls within a large window of time. The timing of these changes is also important to ensure the continued health of the pregnancy, as early udder development or vulvar swelling in horses can indicate problems, such as placentitis, and, in some cases, are followed by abortion . AdditioIn our study, there was a fairly large range of time for when udder development was first noted prior to birth. This range could be due to differences in the close visual access to the rhinoceros, the intensity of the monitoring or recording of anatomical changes in pregnant dams, as well as the level of experience or knowledge of the observers regarding changes in the udder. A median of 21 days, however, correlates with findings in other reports. In Hermes’s study, it was found that the udder development in SWR was typically noted three weeks prior to birth , and a rVulvar edema and the loosening of the tail head and peri-vulvar muscles that occurred at a median of 19 days prepartum in our study are similar to what was reported in Hermes’s study of SWR, in which genital swelling was typically noted 2 weeks prior to birth . ReportsMilk dripping, or “teat waxing”, is an important predictor of impending parturition in horses, as it should occur within 1–4 days before the beginning of phase I of labor  . This complements both Hermes’s findings, in which the first stage of labor started approximately 5–7 h prior to birth , and finPhase II of parturition is characterized by active labor with concerted abdominal and uterine contractions ending with the expulsion of the fetus. In horses, phase II begins with the characteristic “water breaking”, which is caused by the rupture of the chorioallantoic membrane and the subsequent release of allantoic fluid as the fetus enters the birth canal. This is swiftly followed by active labor and the passage of the fetus. In rhinoceros, however, there is a prolonged lag time of up to two hours between the water breaking and the start of active labor. In our study, we found that the “water breaking” could be easily missed or difficult to differentiate from urination due to the variable quality of the videos. Alternatively, the first reliable visible sign of phase II was the presence of the fluid-filled amniotic sac at the vulvar opening. This appears as a shiny, round but taut, white tissue protruding from the vulva. Additionally, the time from when the allantoic sac is present at the vulvar opening until the time that the fetus is expelled is more characteristic of the phase II seen in horses, as it includes the portion of active uterine contractions. Therefore, the presence of the amniotic sac until the passage of the fetus was used as the definition of phase II in our study. Hermes’s 2020 study used a different approach by dividing phase II into two stages. The first stage incorporated the time between chorioallantoic rupture until the fetal membranes were visible at the vulvar opening, whereas the second stage incorporated the active labor portion .The lengths of phase II in our study had median durations of 28 min across all species, 63 min in the BR, 31 min in the GOHR, and 20 min in the SWR. With the exception of the BR, these median values align with the expected duration of 20–30 min of phase II in horses  . Hermes’s study reports the placenta passing around 3 h after birth , and oneReports of retained placentas amongst rhinoceros are scarce, with only two occurrences in our dataset, leading to a prevalence of 12% (2/16). The reported prevalence of the retention of fetal membranes in horses can vary by species but typically falls between 2 and 17% and is often associated with a prolonged phase II of birth   of births were associated with posterior presentation . Only 1 These findings are significantly different from what is found in horses, in which anterior presentation is considered normal and abnormal fetal postures and positions are widely documented   amongst all the species of rhinoceros in our data. While this skew may be due to the overall small sample size of calves where sex was known (n = 32), this finding could have significant impacts on the conservation efforts for the ex situ rhinoceros population by creating limitations for the resources to house solitary surplus males. Sex skews have been previously identified in the BR population in the United States .Our findings show that 13% (6/46) of all the calves delivered were stillborn. This rate is notably higher than what has been reported for horses, with a prevalence between 1.2 and 4.5%, depending on the report ,55. The According to our data, dystocia appears to be rare in rhinoceros, with a prevalence of only 6% (2/35). This is low compared to the prevalence of 10.1% in horses according to a retrospective study from 2012 . This reOnly two dystocias were included in our study; both were associated with GOHR, resulting in a 14% prevalence of dystocia amongst the GOHR births (2/14). One dystocia involved a nulliparous dam and was associated with fetal malpositioning, resulting in a stillborn calf due to a prolonged phase II. The second dystocia involved a multiparous dam and resulted in a stillborn calf; however, there is no additional information to indicate the cause for the complicated birth. Only one report in the literature describes an abnormal birth and veterinary intervention in rhinoceros. This report involves a multiparous 17-year-old GOHR under managed care with a prolonged phase II time lasting 31 h before a fetotomy was performed. The dystocia was caused by the fetal malpositioning of the calf due to a flexed forelimb. Post-mortem evaluations revealed that this calf had multiple congenital deformities, including cerebral aplasia. The dam recovered and resumed ovarian cycling after the fetotomy; however, the report does not describe whether the dam produced any live calves following this procedure .More data are needed to determine the common causes of dystocia in rhinoceros, although, based on the few reports available, fetal positioning appears to be an important factor. To the best of the authors’ knowledge, there are no reports of premature placental separation or periparturient uterine hemorrhage in rhinoceros; however, the development of these pathologies is possible. It is likely that dystocia in rhinoceros occurs more commonly than what is reflected in the literature; however, complicated births still appear to be rare when compared to equids. This is presumably a result of the compact build of rhinoceros calves, where the lack of long slender legs and necks makes abnormalities of fetal posture less likely.Reports of neonatal landmarks after birth in rhinoceros, such as the time to standing or nursing, are sparse. However, knowing what is expected after a calf is born is important to be able to recognize when certain milestones are delayed and could indicate possible abnormalities. Nineteen calves were included in this study, although not all landmarks were included for each calf. Based on a video review, if the birthing stall was well bedded with absorptive or non-particulate substrate, such as hay or straw, a healthy calf would pull itself into sternal recumbency within 10 min, with a median duration of 7 min. Calves were standing by around 1 h after birth, with a median time of 52 min, which correlates with Hermes’s finding of calves standing about 55 min after birth .Interestingly, we found that the SWR calves stood faster than the GOHR calves, with median times of 30 min amongst the SWR and 64 min amongst the GOHR. The cause for this is unknown and could be associated with external factors, such as the substrate used in the different housing styles for these two species, as the SWR were more commonly housed in large stalls, whereas many GOHR gave birth in smaller boma-type enclosures. More data are needed to determine whether this is a consistent finding between the two species regardless of the substrate or birthing enclosure used.Calves typically nursed around 2 h after birth, with a median duration of 127 min. This follows what is seen in horses, with foals expected to stand by 1 h after birth and nurse by 2 h . Hermes’The frequencies of the anterior and posterior presentation in the calves were similar between the GOHR and SWR;Posterior presentation of the calf was associated with a 2.5-times longer phase II of parturition in the GOHR compared to the SWR;The observed frequency of stillbirth was five times higher in the GOHR compared to the SWR;Dystocia and retained placentas were rare compared to horses;Rhinoceros dams will give birth in both lateral recumbency and while standing;Calves are typically standing within an hour after birth and are nursing 1–2 h later; however, the SWR calves stood twice as fast compared to the GOHR calves;The proposed start and end points for the three phases of parturition in rhinoceros are as follows: Phase I begins with two or more signs of impending parturition, such as restlessness and tail flagging/curling, and it ends with the presence of the amniotic sac present at the vulvar lips. Phase II begins with the presence of the amniotic sac at the vulvar lips and ends with the expulsion of the fetus. Phase III begins with the expulsion of the fetus and ends with the passage of the fetal membranes.


In the absence of medical necessity, opting for caesarean sections exposes mothers and neonates to increased risks of enduring long-term health problems and mortality. This ultimately results in greater economic burden when compared to the outcomes of spontaneous vaginal births. In Switzerland around 33% of all births are by caesarean section. However, the rate of caesarean sections without medical indication is still unknown. Therefore, we devise an identification strategy to differentiate caesarean sections without medical indication using routine data. In addition, we aim to categorize the influencing factors for women who undergo spontaneous vaginal births as opposed to those with caesarean sections without medical indication.We use Swiss Federal Statistics data including 98.3% of all women giving birth from 2014 to 2018. To determine non-medically indicated caesarean sections in our dataset, we base our identification strategy on diagnosis-related groups, diagnosis codes, and procedure classifications. Subsequently, we compare characteristics of women who give birth by non-medically CS and external factors such as the density of practicing midwives to women with spontaneous vaginal birth. Logistic regression analysis measures the effect of factors, such as age, insurance class, income, or density of practicing midwives on non-medically indicated caesarean sections.Around 8% of all Swiss caesarean sections have no medical indication. The regression analysis shows that higher age, supplemental insurance, higher income, and living in urban areas are associated with non-medically indicated caesarean sections, whereas a higher density of midwives decreases the likelihood of caesarean sections without medical indication.By identifying non-medically indicated caesarean sections using routine data, it becomes feasible to gain insights into the characteristics of impacted mothers as well as the external factors involved. Illustrating these results, our recommendation is to revise the incentive policies directed towards healthcare professionals. Among others, future research may investigate the potential of midwife-assisted pregnancy programs on strengthening spontaneous vaginal births in absence of medical complications.The online version contains supplementary material available at 10.1186/s12884-023-06070-x. The mode of birth relies on the condition of the mother and the neonate. The child is either born spontaneously, by instrumental birth, or via a caesarean section (CS). Desirable results linked to CS, such as reduced maternal or neonatal mortality or morbidity, are attainable only up to a specific national ratio . No imprIn this paper, we categorize CS into two primary groups: planned and emergency. Planned CS represents a planned intervention, which may be conducted upon or without medical indication. Women might prefer a planned, non-medically indicated CS  due to social norms, emotional or personal experiences , 9. DuriMedia reports presenting an inappropriate image of CS reduce women’s perception of the associated risks . NeverthIn this paper, we present a novel approach on identifying cases of non-medically indicated CS in routine data by using Swiss hospital claims data from 2014 to 2018. We examine factors that are associated with a higher likelihood of giving birth via CS in absence of any medical indication.n = 430,920). The dataset is provided by the Federal Statical Office containing claims data of Swiss hospitals. As neither a corresponding diagnosis-related group (DRG), procedure classification (represented by the Swiss operation classification (CHOP)), nor a diagnosis code (ICD-10-GM) is available for non-medically indicated CS, we estimate the number of non-medically indicated CS based on various criteria. Nevertheless, the dataset does not provide information about whether a woman expresses a preference for giving birth via CS or not.The study is based on the national dataset “Medical Statistics of Hospitals” which includes all women having given birth in Swiss hospitals between 2014 to 2018 ”. We assume that having completed 33 weeks of pregnancy allows for spontaneous birth without fearing negative effects neither for the mother nor the neonate – every birth before 33 completed weeks classifies as extremely (less than 28 weeks) or very (28 to 32 weeks) preterm birth [We obtain cases of CS without medical indication by data selection as represented in Fig. rm birth . FurtherSecond, diagnoses that do not allow for vaginal birth such as malpresentation of the foetus, maternal hip anomalies, or women with indicated labour who later change to an emergency CS are excluded from the dataset . The less complex DRG codes for CS are O01F (2014–2016), O01G (2017), and O01H (2018). We hypothesize that women with a CS in absence of any medical indication could have given birth spontaneously instead. This makes the group of SVB comparable to non-medically indicated CS.Furthermore, we integrate supplementary data sources to enrich the explanatory power of the present study. Information is collected for per capita net income and nursing staff per hospital bed, both at the cantonal level and on an annual basis. For the identification of differences in the level of urbanity, we use information from the statistical atlas of Switzerland. Additionally, the Swiss society of midwives provides information on the number of practicing midwives per canton.We provide descriptive statistics to illustrate the characteristics of the two birth mode groups. Secondly, to analyse significant differences between the mean values of mothers giving birth by non-medically indicated CS versus SVB, we use independent-samples t-test. Thirdly, logistic regression analysis with a 5% significance level identifies the impact of factors associated with a higher likelihood of giving birth by CS without medical indication. The regression includes the following independent variables: age, insurance status, urbanity level , number of midwives per 1,000 births, number of nursing staff per hospital, and income per capita.Logistic regression analysis especially suits this research as only two outcomes are assumed: non-medically indicated CS and SVB. Furthermore, the logistic regression calculates the impact of the chosen independent variables on the chance of giving birth by non-medically indicated CS. A higher log odds ratio indicates a higher chance of giving birth by non-medically indicated CS. Similar approaches were already taken by previous studies for assessing the impact of various non-medical factors on non-medically indicated CS , 28. We The average number of annual births in Swiss hospitals from 2014 to 2018 was approximately 86,200 . Most women with a non-medically indicated CS live in urban areas (67.9%) followed by suburban (17.1%) and rural areas (15.1%). Women with SVB live mostly in urban areas (63.3%) followed by rural (19.2%) and suburban areas (17.2%).In Switzerland, individuals have the choice to opt for supplementary insurance coverage for inpatient medical services in addition to mandatory insurance which covers basic services. Comparing this with supplemental insurance types, i.e., semi-private or private, the insured pay higher fees for additional services such as staying in a single or double-person room, and timely-preferred treatment by a specialist. The percentage of privately insured women with a non-medically indicated CS was double of those with SVB (8.8% vs 4.1%). Further, women with non-medically indicated CS were less often solely mandatorily insured than those with SVB (75.9% vs 85.5%).DRG cost weights determine the payment of each inpatient case. Non-medically indicated CS were covered on average with a cost weight of 0.864 in 2014 remaining at the same level in 2016 and then decreasing to 0.791 in 2018. SVB showed a lower cost weight, which was 0.581 in 2014 decreasing to 0.545 in 2016 and followed by a slight increase to 0.564 in 2018. Therefore, SVB payment was generally lower compared to non-medically indicated CS across all years.S = 0.155, p < 0.01), i.e., woman with a higher income tend to have supplemental insurance. All variables differ in their mean values with statistical significance (p < 0.001) between the two birth modes.Some differences in the characteristics of the mothers belonging to either group of birth modes were already observable. Table p < 0.001). A lower age category decreases the risk of giving birth by CS without medical indication, whereas the category 45–49 years served as a reference category. Additionally, for women with mandatory or semi-private insurance the odds ratio of giving birth by non-medically indicated CS is significantly lower compared to women with private insurance (reference category). For women in urban areas, the likelihood of a CS without medical indication increases compared to women in rural areas (reference category). Furthermore, a higher number of practicing midwives per 1,000 births reduce the log odds ratio by 0.019. The number of nursing staff per bed is also associated to the birth mode. The more nursing staff available per bed, the higher the chance of undergoing a non-medically indicated CS. Lastly, income per capita impacts the decision on the birth mode. A CHF 10,000 increase in annual income per capita raises the log odds ratio by 0.168.For the logistic regression  is highly imbalanced. The performed logistic regression has an area under the curve (AUC) of 0.625, which indicates an acceptable quality of the model regarding the aim of this research.This paper aims to identify the percentage of non-medically indicated CS in Switzerland and second, to uncover levers for a change in the birth practice. Both questions are analysed based on a large Swiss dataset. The share of non-medically indicated CS amounts to almost 8% of all CS, which are more than 2,200 births annually in absolute terms. Research from the neighbouring country Germany reports one out of ten CS as not medically indicated. Additionally, the average non-medically indicated CS ratio in Germany is around 1% of the total number of births . Other cThe DRG cost weight for non-medically indicated CS generates higher payments compared to SVB. Reasons for this imbalance are the costs of expensive infrastructure  and higher personnel requirements (such as interdisciplinary operation teams). On the other hand, a higher level of uncertainty exists for SVB. On the contrary, there is a greater degree of uncertainty associated with SVB as it is inherently less predictable and demands higher time and personnel resources. Furthermore, resources must be kept available such as additional staff for an emergency CS or operating room capacities although they might not be used. Hence, for future infrastructure  planning, also the non-usage of available resources needs to be considered when setting payment rates.The average age of the childbearing mother does not significantly differ between the two investigated modes of birth. The largest age category is at both birth modes 30–34 years. However, for non-medically indicated CS the group of 35–39 years follows whereas for SVB the category of 25–29 years ranks second. Hence, women with non-medically indicated CS are in general slightly older than women having given birth by SVB. This is also supported by previous research , 31 whicFurther, a difference in insurance status of the included women exists. A higher ratio of women with semi-private or private insurance is observable in the non-medically indicated CS group compared to SVB. Similar findings were also reported by Womack et al.  for the The number of midwives per 1,000 births per canton might have an impact on the likelihood of a woman being accompanied by a midwife during pregnancy. Research showed that women who benefit from a midwife-led care program are more likely to give birth spontaneously , face beThe paper identifies decisive factors for the decision on the mode of birth. To the authors’ knowledge, this is the first paper that chooses the presented approach to identify non-medically indicated CS in Switzerland, as corresponding procedures, diagnoses or DRG codes do not exist. Age, number of nursing staff per bed, and income per capita are significantly higher for women with non-medically indicated CS and these factors also increase the log odds ratio of a CS, although no medical indication is present. On the other hand, women also show significant differences in the insurance class, urbanity score and the number of midwives per canton. Having mandatory insurance, living in rural areas or in areas with a high number of practicing midwives per 1,000 births decreases the chance of CS without medical indication.As every empirical study, also this analysis faces some limitations. First, there is no classification code for non-medically indicated CS, whereby only an approximation of the number of non-medically indicated CS cases is possible. Second, despite the large amount of cases of a national dataset, the analysed data does not contain personal  nor interpersonal (such as care during pregnancy or obstetrician’s tendency) factors. Additionally, clinical information is not available and it is unknown for example whether the woman is nulliparous, primiparous, or multiparous. Therefore, it is not possible to distinguish whether a non-medically indicated CS follows a previous CS. Having such variables available would improve the predictive power of the ROC curves for the logistic regression model. Furthermore, a mandatory nationwide collection of the information specifying the classification according to Robson’s proposition would further strengthen the explanatory power of research on uncovering reasons and outcomes for different birth modes in Switzerland.We develop a strategy for identifying non-medically indicated CS in routine data in absence of any unique identifying factor. CS without medical indication can be determined based on a composition of DRGs, procedure classifications and diagnoses. Thereby, this study reveals that at least 8% of CS were on a non-medically indicated basis between 2014 and 2018. Factors significantly associated to non-medically indicated CS are higher age, supplemental insurance, higher income, more available staff at the hospital and living in urban areas. In contrast, living in an area with a higher density of practicing midwives significantly decreases the likelihood of giving birth by non-medically indicated CS, and thereby increases the likelihood of giving birth spontaneously. Health policy implications derived from this research are fourfold: first, obstetricians should be sensitized to special characteristics of women undergoing CS in absence of any medical indication and be encouraged to communicate the risks for both the mother and the neonatal more explicitly; second, the density of practicing midwives should be increased in case they can reduce the number of non-medically indicated CS and further promote the benefits of spontaneous birth; third, the DRG cost weights for non-medically indicated CS and SVB should be aligned to avoid inadequate incentive mechanisms to prefer non-medically indicated CS over SVB due to higher reimbursement rates. Giving birth to a child is different from typical treatments provided in a hospital, as personal beliefs and preferences must be taken into consideration.Additional file 1. Diagnoses used to exclude cases from the not medically indicated CS dataset.Additional file 2. Treatments used to exclude cases from the not medically indicated CS dataset.


The SARS-CoV-2 (COVID-19) pandemic impacted the health systems between and within countries, and in the course of the pandemic sexual and reproductive health services were the most disrupted. Findings from high-income settings have reported significant changes in preterm birth prevalence during the pandemic period. To understand the possible effects of the COVID-19 pandemic on preterm birth numbers at the Brazilian national level. We compare the number of preterm deliveries during the COVID-19 pandemic period (2020 and 2021) with previous years. We conducted a population-based cross-sectional study taking the period from January 2017 to December 2021 to account. We use individual-level live births data from the Brazilian Live Birth Information System (SINASC), and we estimate the odds ratio (OR) of preterm deliveries using propensity score weighting analysis in Brazil and its regions. During the study period (from 2017 to 2021), about 2.7 million live births were recorded per year, and the missing value for gestational age at delivery was less than 1.5%. The preterm birth prevalence slightly increased during the COVID-19 pandemic compared to the pre-pandemic period . After adjusting for sociodemographic variables, the OR of preterm births in Brazil has significantly increased, 4% in 2020 , and 2% in 2021, compared to 2019. At the regional level, the preterm birth pattern in the South, Southeast and Northeast regions show a similar pattern. The highest odds ratio was observed in the South region . However, we also observed a significant reduction in the ORs of preterm births in the northern region during the COVID-19 pandemic  and . Our analysis shows that the pandemic has increased regional variation in the number of preterm births in Brazil in 2020 and 2021 compared to the pre-pandemic years. In addition to controversial health policies, conflicting messages and long-time central government resistance to implementing population mobility restrictions2, Brazil was one of the most affected countries by COVID-19 worldwide. Pregnant women were also a risk group, as maternal mortality skyrocketed during the pandemic3.The COVID-19 pandemic impacted Latin American countries as hard as in more developed locations. Due to the sanitary crises, we saw in many countries disrupting health systems, and as consequence, mortality exceeded its usual numbers and life expectancy reductions in many countries4. Studying preterm birth is important because it is the primary cause of neonatal deaths, and its prevalence is rising in most low- and middle-income countries, despite many efforts to revert it6. While several risk factors have been well-established, the key factor responsible for preterm deliveries remains unknown in half of the cases7. Since the onset of the pandemic, several studies have identified an association between COVID-19 infection and adverse perinatal outcomes, such as stillbirths and premature deliveries11. These findings are also contradictory because some analyses indicate that the number of preterm deliveries increased during the pandemic, while other studies suggested a reduction in such types of pregnancies11.Maternal mortality is also an important proxy for the quality of country's health services. Another obstetric condition that is sensitive to suboptimal clinical care is preterm birth12. The SARS-CoV-2 infection is a systemic inflammatory disease; therefore, we may argue that it could lead to preterm birth. For example, among women with SARS-CoV-2 pneumonia, empirical evidence shows an increased preterm birth rate13. However, the infection itself may not represent the whole mechanism related to preterm delivery.One of the most important underlying mechanisms for preterm birth is the inflammatory condition. The systemic inflammation may trigger cervical effacement and uterine contraction through increasing prostaglandins14. Other studies also indicate a decrease in preterm birth rates16, although the same empirical evidence was not corroborated elsewhere that fail to identify differences in the number of preterm pregnancies17.In addition, we may also argue that changes in individual behavior are associated with lockdown and other population restrictions policies, implemented to mitigate SARS-CoV-2 dissemination, and that may have influenced to some extent the number of preterm births. As an example, an Australian study showed a lower risk of preterm birth in pregnant women during lockdowns in comparison to those born before the pandemicDespite inconclusive findings, there is a consensus that the COVID-19 pandemic period brought many challenges to the country’s health systems, and there is still scarce information about its real consequences on perinatal health while considering low- and middle-income countries. Therefore, in this study, we aim to assess the changes in preterm birth counts in Brazil and its regions, by comparing the number of preterm deliveries during the pandemic (2020 and 2021) and pre-pandemic periods .18. The SINASC is an e-birth registration system developed by the Department of Informatics of the National Unified Health System (DATASUS). This system was implemented in 1990. The data are collected routinely immediately after each birth through a standardized document (declaration of live births), which was updated in 2010 to ensure a better quality of the information recorded19. The updated version included many important variables for the study of preterm birth, such as sociodemographic and obstetric variables.We performed extensive use of the publicly available microdata of live birth, collected by the Brazilian Ministry of Health, and launched by the Brazilian Live Birth Information System (SINASC in Portuguese)http://svs.aids.gov.br/dantps/cgiae/sinasc/, and we consider all live births equal or superior to 22 weeks, from January 2017 to December 2021. We extracted individual-level data regarding gestational age at birth, maternal age, marital status, ethnicity, schooling (as a proxy of women's income), parity, gravidity, mode of delivery, region and federal state of residence, number of living children, number of antenatal care (ANC) visits, and newborn's weight and sex. These variables are available in the SINASC for each birth, and they are highly associated with preterm delivery. We did not exclude multiple pregnancies and neonates with congenital anomalies for the analysis. All categorical variables were converted to binary dummies by using the one-hot encoding procedure. Less than 1.5% of the data had missing or unknown information. Notwithstanding, SINASC data quality has recently shown enormous improvement. Of course, while considering more disaggregated geographical levels, the data may still need some adjustments and corrections. For this study, we work with Brazil and great regions, and that reduces significantly defective concerns such as under-registration of birth counts; as in Brazil and its regions, the rate of underreported data is generally less than 1%, except in the North and Northeast regions where the rate is about21 1.7%. In addition, Castanheira and Kohler considered inadequate to apply any correction method to birth registrations, given the recent fertility dynamics in the country22. Lima et al.23 also show that recent SINASC information does not require data corrections at lesser disaggregated levels, such as Federal States and great regions. However, we acknowledge that the unprecedented burden on the health system during the pandemic may have influenced the data quality. The study protocol was published elsewhere24.The data was downloaded , and updated  from 25. We created four stacked datasets  and we added, for each dataset, two dichotomous variables of interest: one to indicate whether the birth was preterm (y = 1) and (y = 0) otherwise, and another measure indicates the period, i.e. the current year in the dataset (z = 0) vs. the following year (z = 1). This last variable is useful for identifying the control group (preterm births occurring in years before COVID-19) and the treatment group (preterm deliveries occurring during the pandemic).To reduce the influence of past trends in prematurity prevalence, we restrict our preterm birth analysis to pairwise years comparison, initiating from 2017 until 2021. We did not include data before 2017 to avoid the influence of the Zika virus outbreak (between 2015 and 2016) on birth counts and overall fertility27. PSW was designed to control for selection bias in non-experimental studies, for which it is desirable to assess the average effect of some variable that emulates a control/treatment process. Propensity scores are used to match untreated versus treated individuals, understanding that there is a probability of these last being exposed to a certain stimulus or intervention28.Our analysis was based on a quasi-experimental approach using a Propensity Score Weighting (PSW) methodAs the first step, a multiple logistic regression analysis was used to fit the binary control variable (z) as a function of the mother’s and obstetrics’ characteristics: age, ethnicity/skin colour, schooling, parity, mode of delivery, number of previous children, marital status, number of antenatal care visits and new-born weight. With the regression estimates, we extracted a vector (e) that gives the probability of treatment assignment to a random individual conditioned to a given set of covariates (x), i.e. e(x) = P (z = 1| x).The vector (e) is called the Propensity Score, and it was used to control for selection bias and to derive the weights of a second regression model. The control was made by pruning samples corresponding to the tails of the Propensity Score vector, to keep only samples that can be considered comparable to each other. Figure The set of weights was estimated as follows: for the individuals in the treatment group, w = 1/e(x), and for the individuals in the control group w = 1/(1-e(x)). As a final step, we estimate a new regression, fitting the outcome of interest (preterm birth) controlled by the covariates and using the propensity scores as weights.18. In Table About 2.7 million live births were recorded annually from 2017 to 2021Overall, in Brazil, the preterm birth counts were around 11%, and this number did not change much compared to pre-pandemic years, in this case, 2019. Also, in terms of the mother’s characteristics, we did not identify considerable changes in the last three years of our analysis.In Table In addition, the pairwise comparison for the period 2017 to 2019 shows small or non-significant changes in the ORs of preterm births, and the odds ratios of preterm pregnancies fluctuated between values of below and above 1%. This means that during the pandemic the chances of preterm deliveries have increased somewhat to two and four per cent.In Fig. Our finding showed a significant change in caesarean delivery rate during the pandemic period compared to the previous period , Table Using Ministry of Health data, we assessed the odds ratios of preterm births in Brazil and its regions, before and during the pandemic. Our results indicated that, during the pandemic years of 2020 and 2021, preterm births have significantly increased as compared to pre-pandemic periods. This increase was not homogeneous across the country, and in certain regions, the pandemic has disrupted previous decline patterns or even accelerated the past trend of preterm deliveries growing; as observed in Northeastern, Southeastern, and Southern regions.30.The ethnicity (indigenous women), low level of education, low number of antenatal care visits, and multiparity, extreme maternal ages, were associated with an increased risk of PTB. These data are similar to the findings of other population-based studies31; the same pattern was also observed in Brazil, where the quality of ANC was low (only 35.8% of the study participants had adequate), In addition, the risk of inadequate ANC was higher among pregnant women with black/brown skin colour and multiparous when compared to their contra part32. These factors potentially contributed to worsening pregnancy outcomes (including the preterm birth rate), even for married/cohabiting women.Finding from individual studies and systematic review has suggested a global reduction in ANC clinic visits, maternity healthcare-seeking, and unscheduled care visitsDuring the COVID-19 access to the Internet and DICT  was heterogeneous within the Brazilian regions, and municipality, public and private health systems. And, to the best of our knowledge, data regarding the coverage of virtual or remote antenatal care were not available in the database [SINASC], and the ANC visits are not desegregated by the mode of consultation [remote vs in-person]), therefore, we have not considered this variable in our analysis.33, as well as health facilities also were stressed by the high number of COVID-19 cases, and many services could not be properly provided by health units34. This exogenous sanitary problem might have also affected women's antenatal care, especially among those that require more attention from public health services, i.e., mothers from low socioeconomic strata. Uncertainty and economic restrictions caused by the pandemic context may also play an important role in reproduction35, and compromise pregnancy and antenatal care in Brazil.The pandemic brought the attention of health experts and demographers that took the time to understand how COVID-19 could affect birth counts and, for instance, the chances of preterm deliveries in the country. Brazil is a country that suffered excessive mortality due to the COVID-19 pandemic37, and the lack of strategy to mitigate the impact of the pandemic at different governmental levels33. Notwithstanding, the COVID-19 pandemic brought an enormous burden to Brazil's Northern and Northeastern regions and revealed a sudden disruption of health care services39. These setbacks might in turn affect the preterm birth rate.Among Brazilian regions, the Northeast requires special attention because this is a region marked by historically lower socioeconomic development that could be in turn associated with restricted health services access44. This could be partly explained by the measures applied to face the pandemic, which was uncoordinatedly implemented in Brazil36. Regional inequality in health services access and the slow degree of responsiveness of the Brazilian National Health System could have played a role in the unequal pandemic effects on preterm births across Brazilian regions. As previous studies indicate, less sub-national inequality is seen in high-income countries, recognized by strict lockdown policies and with developed health services according to the needs posed by the pandemic. Moreover, Brazil had more severe cases; one out of seven maternities had intensive unit beds, therefore resulting in the phase three delay—concerning receiving proper diagnosis and timely treatment46.Our findings differ from other studies that indicated a reduction in preterm deliveries during the COVID-19 pandemic48.However, our findings suggested a different pattern of preterm birth rate in the Northern region. In the Northern region of Brazil, more than two–thirds of pregnant women did not attend antenatal care, and higher excess mortality , which might have caused severe perinatal outcomes 50.Our study suggested an increased rate of caesarean delivery among preterm babies in 2020, and 2021 compared to previous periods. Therefore, we may speculate that the increased risk of PTB in 2020, and 2021 may be related to non-spontaneous (provider-initiated) preterm birthIt is important to mention that we concentrate our analysis and interpretations on the year's effect only , and we do not get into detail about the other control variables, despite the models have shown important differences in preterm pregnancies among distinguished demographic and socioeconomic groups.20. The analysis of the different geographic regions allowed us to picture preterm birth developments in a country recognized for its regional inequality. The main limitation is related to the study design, which does not allow us to infer causality but only refers to the association between the pandemic and preterm births. We also did not assess the direct impact of COVID-19 on the occurrence of preterm births, and we considered the years 2020 and 2021 as risk factors that caused changes  brought by the pandemic onset. Likewise, our model did not include all variables associated with preterm birth, for example, human development index, availability and access to health services before and during the COVID-19 pandemic, cigarette smoking, BMI, maternal income, unemployment, maternal underlying medical conditions, and maternal infection . We did not assess the prevalence of fetal deaths and the abortion rates. But we recognize that these outcomes could have increased in situations of reduced access to adequate health services, impacting Brazil’s birth rates.This study has some strengths and limitations. Our data covers the entire population of live births in Brazil, with information at the individual levelAlthough we did not see an expressive increase of preterm births, we still argue that the disruption of sexual and reproductive health services may have influenced pregnancy outcomes. Therefore, monitoring the preterm birth rate might be an essential strategy for assessing the quality of maternal and perinatal care and might help providers and policymakers to develop strategies to mitigate the problem.


Cochlear implant (CI) recipients with hearing preservation experience significant improvements in speech recognition with electric–acoustic stimulation (EAS) as compared to with a CI alone, although outcomes across EAS users vary. The individual differences in performance may be due in part to default mapping procedures, which result in electric frequency-to-place mismatches for the majority of EAS users. This study assessed the influence of electric mismatches on the early speech recognition for EAS users.Twenty-one participants were randomized at EAS activation to listen exclusively with a default or place-based map. For both groups, the unaided thresholds determined the acoustic cutoff frequency . For default maps, the electric filter frequencies were assigned to avoid spectral gaps in frequency information but created varying magnitudes of mismatches. For place-based maps, the electric filter frequencies were assigned to avoid frequency-to-place mismatches. Recognition of consonant–nucleus–consonant words and vowels was assessed at activation and 1, 3, and 6 months postactivation.Mdn = −5 semitones). Poorer performance was observed for those with larger magnitudes of electric mismatch. This effect was observed through 6 months of EAS listening experience.For participants with default maps, electric mismatch at 1500 Hz ranged from 2 to −12.0 semitones (The present sample of EAS users experienced better initial performance when electric mismatches were small or eliminated. These data suggest the utility of methods that reduce electric mismatches, such as place-based mapping procedures. Investigation is ongoing to determine whether these differences persist with long-term EAS use.https://doi.org/10.23641/asha.22096523 Adult cochlear implant (CI) recipients with hearing preservation experience significant improvements in speech recognition with electric–acoustic stimulation (EAS) as compared to preoperative performance or postactivation with a CI alone, although performance across EAS users remains widely variable . This vaplace-based maps, have been associated with better speech recognition than spectrally shifted maps based on data from CI-alone vocoder simulations  imaging and estimated the cochlear place frequency. The filter frequencies for specific channels were assigned to match the place frequencies of the corresponding electrode contacts. While this approach eliminates electric mismatches, it can result in spectral gaps that default mapping procedures avoid. Spectral gaps generally result in poorer performance for EAS users , althougThis report assessed the influence of electric frequency-to-place mismatches on the speech recognition outcomes of EAS users within the first 6 months of device use. The study sample included EAS users who were randomized to listen exclusively with either a default map  or a place-based map (no electric mismatch). The hypotheses were that early speech recognition outcomes would be better for EAS users with smaller electric mismatches and that the negative influence of larger electric mismatches would persist over the initial months of EAS listening experience.Preliminary data were reviewed from an ongoing, prospective investigation of performance with default versus place-based maps for CI recipients. The study site institutional review board approved the procedures, and participants provided consent. Participants were randomized to listen exclusively with either a default or place-based map. Procedures were completed at device activation (2–4 weeks postoperatively) and at 1, 3, and 6 months postactivation. Both the research audiologist who completed the assessments and the participants were blinded to the assigned map.Adult CI recipients were considered for inclusion if they underwent cochlear implantation at the study site, received a MED-EL lateral wall electrode array, were 18–80 years of age at the time of surgery, and presented with an unaided hearing threshold of ≤ 65 dB HL at 125 Hz in the implanted ear at device activation. Potential participants who failed the Mini-Mental State Examination  or reporUnaided detection thresholds in the implanted ear were measured behaviorally using pure-tone stimuli presented over insert earphones at each interval. A low-frequency pure-tone average (LFPTA) was calculated from the unaided detection thresholds at 125, 250, and 500 Hz.EAS processor. The acoustic component was fit based on the participant's unaided detection thresholds in the implanted ear. The thresholds were entered into the clinical programming software (Maestro v9), which determined the acoustic cutoff frequency by identifying the frequency at which the detection threshold exceeded 65 dB HL. The acoustic settings were verified using the NAL-NL1 prescriptive targets . The remaining mid- to high-frequency information was logarithmically distributed across the active channels.For participants randomized to listen with a place-based map, the electric filter frequencies were assigned to align low- to mid-frequency information with the cochlear place frequencies. Postoperative CT imaging was obtained for all cases using a Morita cone-beam CT scanner, and the image was uploaded to the OTOPLAN software (CAScination AG and MED-EL Corporation). Two reviewers manually identified cochlear anatomical landmarks  and individual electrode contacts for each CT image; those landmarks were used by the software to calculate the AID for each electrode contact, as previously described . The cocSpeech recognition was assessed using tasks of vowel and word recognition. Vowel recognition tasks have been shown to be sensitive measures of the influence of electric mismatches on speech recognition with a CI alone . The assElectric frequency-to-place mismatch was quantified as the semitone deviation between the electric center frequency and the SG place frequency for the electrode contact closest to the 1500-Hz cochlear place (~267°). The 1500-Hz place frequency was selected because it has been shown to be an important region for frequency alignment in CI simulations evaluating speech recognition .lme package (Linear mixed models (LMMs) implemented in R using the  package  assessed package  to norman = 15) or a place-based map (n = 6). Age at implantation ranged from 22 to 78 years, with a median of 66 years. Eleven participants were implanted with a Flex24 array; six, with a Flex28 array; and four, with a FlexSOFT array. All cases had a full insertion of the electrode array. The median AID of E1 was 503°, with a range of 370°–691°. For participants with default maps, electric mismatch at 1500 Hz ranged from 2 to −12.0 semitones (Mdn = −5 semitones),Supplemental Material S1.The data included 21 participants  who were randomized to listen with either a default map  = 3.6, p = .050, and achieved significance for CNC word recognition, F = 23.5, p < .001, with participants experiencing improvements in speech recognition over time. For CNC words, there was a significant interaction between interval and electric mismatch, F = 11.7, p < .001, reflecting the fact that participants with minimal mismatches experienced more substantial improvements in performance over time than participants with larger magnitudes of mismatch. This interaction between interval and mismatch was not observed for vowel recognition, F = 1.4, p = .283.F = 5.5, p = .027, and for CNC word recognition, F = 4.6, p = .041, with poorer performance observed for participants with larger magnitudes of electric mismatch on both tasks. The interaction of electric mismatch and interval was not significant for vowel recognition, F = 0.59, p = .561, or for CNC word recognition, F = 1.4, p = .252. Taken together, these results indicate that EAS users with smaller magnitudes or no electric mismatch had better speech recognition scores than EAS users with larger magnitudes of electric mismatch over the first 6 months of listening experience.In a second set of analyses, these LMMs were expanded to include the data from the participants with place-based maps. p ≥ .259); age at implantation was not significant for CNC words (p = .510) and trended toward significance for vowel recognition (p = .056).Additional analyses were conducted to evaluate other factors thought to affect performance in EAS users . No significant main effects were observed when the models that included the data from all participants were expanded to include LFPTA  or place-based maps that eliminated electric mismatches for low- to mid-frequency information. Poorer speech recognition was observed for EAS users with larger magnitudes of electric mismatch. For example, models including all participants predict poorer performance at 6 months postactivation for individuals listening to maps with 6 semitones of electric mismatch as compared to maps with no electric mismatch by 21 and 22 RAUs for vowel and word recognition, respectively. These data suggest that electric frequency-to-place mismatches may influence the speech recognition outcomes of adult EAS users—at least within the initial 6 months of device use. The preliminary patterns of performance for EAS users with place-based maps suggest the utility of methods that minimize or eliminate electric mismatches to support early speech recognition.The early effects of electric frequency-to-place mismatches for EAS users corroborate the previously observed performance differences for participants with normal hearing listening to EAS simulations. In both paradigms, we observe better performance with place-based maps than for spectrally shifted maps . For insOne factor to consider when evaluating the present place-based mapping procedure is that it may result in a spectral gap between the acoustic and electric outputs. Default mapping procedures limit spectral gaps by assigning a single frequency to the acoustic cutoff and electric low-frequency filter. The poorer performance with spectral gaps for EAS users and listeners for EAS simulations  has not Another factor to consider is electric-on-acoustic masking. For CI recipients with electrode contacts that reside close to or within the region of functional acoustic hearing, the electric current spread from apical electrode contact(s) may introduce substantial masking of the low-frequency acoustic cues . This coThese preliminary data indicate that electric frequency-to-place mismatches influence the early performance of EAS users, although there are limitations worth consideration. This report estimated the cochlear place frequency using the SG frequency-to-place function described by Another limitation is the modest sample size of the current study, which is not sufficient to assess the relationship between electric mismatches, AID of E1, and other device and mapping variables that have been observed to influence the speech recognition of CI recipients, such as angular separation between the electrode contacts  and filtThese preliminary data suggest that EAS users experience better speech recognition when electric frequency-to-place mismatches are minimal and that the negative effects of larger magnitudes of electric mismatches are observed up to 6 months of listening experience. Methods to minimize electric mismatches, such as place-based mapping procedures, may support better early speech recognition for the population of patients similar to the participants in the present experiment. Ongoing work will evaluate the patterns of speech recognition and acclimatization to varying magnitudes of electric frequency-to-place mismatches with long-term device use.mdillon@med.unc.edu).The present preliminary data are available by e-mailing Margaret T. Dillon (10.1044/2022_AJA-21-00254SMS1Supplemental Material S1Click here for additional data file.


Water must be separated from water-in-oil (W/O) emulsion because of the corrosion it brings to the relative equipment in the process of transportation and storage. It is an effective method to apply external electric field to achieve high performance of separating small, dispersed water droplets from W/O emulsion; however, the coalescing micromechanism of such small salty droplets under AC electric field is unclear. In this paper, molecular dynamics simulation was adopted to investigate the coalescence and separation process of two NaCl-aqueous droplets under AC electric field and discuss the effect of AC electric field frequency, as well as the time required for contacting, the critical electric field strength, the dynamic coalescence process and the stability of the final merged droplet. The results show that the critical electric field strength of the droplet coalescence increases with the increase of frequency, while the time required for droplet contacting becomes shorter. The shrinkage function curve was applied to characterize the droplet coalescence effect and it was found that the droplets coalescence and form a nearly spherical droplet under the AC electric field with a frequency of 1.25 GHz and strength of 0.5 V/nm. When the electric field frequency is 10 GHZ, the merged droplet presents a periodic fluctuation with the same period as the AC electric field, which mainly depends on the periodic movement of cations and anions under the AC electric field. The results can provide theoretical basis for the practical application of electrostatic demulsification technology in the petroleum or chemical industry from the microscopic perspective. At present, as many oil fields in the world start to enter a high moisture content period, the water content of the crude oil produced increases gradually. In the process of transportation, storage and reprocessing after exploitation, the relative equipment might be corroded, resulting in the reduction of the working efficiency and the service life of the equipment. Therefore, water in the W/O emulsion must be removed by some techniques for crude oil dewatering, such as swirling method , ultrasoMuch research was conducted to reveal the required conditions to coalesce and effectively improve dewatering efficiency ,13,14,15Molecular dynamics method describes the interactions between atoms in the simulation system based on some potential functions with the accuracy parameters, and provides a powerful tool to study nano/micro phenomena from a molecular level ,23,24,25The above results presented some insights into the coalescence process and discussed some impact factors; however, more detailed characteristics of the ionic nanodroplets throughout the coalescence process seem to be undeveloped, especially under AC electric field. In this paper, to reveal the unclear microscopic effect mechanism of ions, water molecules, electric field form and strength on the dynamic coalescence and breaking-up processes of the ionic droplets, the molecular dynamic simulation was employed to investigate the coalescence and break-up behaviors of two ionic water droplets under the effect of AC electric field. Furthermore, we systematically discussed the effect of electric field frequency and strength on the processes of droplet deformation, motion and coalescence from molecular perspective. Additionally, the oscillation phenomenon of the coalescence droplet was also found.3 and the initial distance between the centroids of the two droplets was 8.0 nm. To demonstrate the interaction and motion relationship of the two droplets more clearly, the droplet at left was numbered as droplet 1 and shown in red, and the right one was numbered as droplet 2 and shown in green. Water molecules are represented by the SPC/E model, which is successfully applied to investigate the wetting behavior of water molecules and other phenomena [iq, jq is the amount of charge of atoms i and j, ijr is the distance between atoms i and j, and ijσ and ijε represent the scaling parameters and energy parameters of the interaction between atoms i and j. ijσ and ijε between different particles can be calculated according to the Lorentz-Berthelot mixing rule [To simply the simulation model of separation system, Na+/Cl− ions are applied to represent the general ions in the water droplet. The initial model of the simulated system is shown in henomena ,31,32. Ting rule  as folloE is applied to the system, each atom is subjected by an external electric field force of ieF = iEq and the direction of the electric field force is determined according to the type of charge iq. Firstly, the simulation system with the two droplets kept at the initial position was first relaxed for 1 ns without applying an electric field to minimize the energy of the system. Then, several of the AC electric fields of E = 0.40~1.50 V/nm with different frequencies are applied to the system to study and analyze the coalescence and separation characteristics of the two nanodroplets, and discuss the effect of the electric field frequency on the critical electric field strength of coalescence and the droplet deformation. Taking the electric field of E = 0.50 V/nm as an example, The LAMMPS package  was usedElectric field strength has an important impact on the coalescence and separating process of nanodroplets, and furthermore, a critical electric field exists ,14,15,37E = cE and E = cE + 0.01 V/nm. When the AC electric field frequency is 1.25 GHz as seen in E = 0.59 V/nm. While a daughter droplet separates from droplet 2 at the right end after 2 two droplets contacting 68 ps under electric field E = 0.60 V/nm, causing partial fracture. According to the physical definition of the critical electric field strength, the critical electric field strength is cE = 0.59 V/nm at the condition with the AC electric field frequency f =1.25 GHz. When the AC field frequency f equals 5.0 GHz, the 2 droplets coalescence at 0.71 V/nm and form a big spherical droplet at t = 562 ps  at the condition with three different electric field frequencies, as well as the corresponding information for the case with DC electric field (noted as f = 0 GHz) are listed in cE increases gradually as the AC field frequency f increases, and the time required for contacting (0t) under the corresponding conditions shows a slight decrease.t < 0 ps) under the electric fields with frequency of 1.25, 5.0, 10.0 GHz and electric field strength of 0.50, 0.70, 0.80, 1.20 and 1.50 V/nm. As can be seen in E is 0.50 V/nm, indicating that droplet 2 is basically spherical throughout the simulation. Therefore, the polarization effect of the electric field on the droplet is very limited at electric field E = 0.50 V/nm. However, when the electric field strength increases to 0.70, 0.80, 1.20 and 1.50 V/nm, the deformation of droplet 2 always increases sharply within 6 ps before contacting with the droplet 1 (−6 ps < t < 0 ps). This is because the polarization induced by electric fields becomes obvious and the droplets are stretched in the electric field direction.As can be seen in f is 1.25 GHz. There are two main reasons for this. One is that the movement of ions in droplet 2 causes the sharp fluctuation of droplet shape. The other is that droplet 2 has sufficient time to respond to the change of electric field and then the shape deforms accordingly when the electric field frequency f is small. At t = −32 ps, the deformation of droplet 2 at the electric field E = 0.70, 0.80 and 1.20 V/nm is greater than that at electric fields with frequency of 5.0 GHz, and the deformation degree is 1.59, 1.88 and 1.47, respectively (see t = 0 ps), the deformation degree is almost the same at electric fields E = 0.70, 0.80 and 1.20 V/nm for the 2 cases with frequency of 1.25 GHz and 5.0 GHz. This indicates the droplet 2 deforms less at the case with frequency f = 1.25 GHz than that at frequency f = 5.0 GHz within the same time period (−32 ps < t < 0 ps). As the frequency increases up to 10.0 GHz, the electric field strength changes too fast, droplets are too late to deform accordingly and can only be continuously stretched under the effect of the AC electric field. Thus, the deformation curves of droplet become relatively smoother, especially at E = 1.50 V/nm.The deformation of droplets is not only affected by the electric field strength but also by the frequency. From comparative analysis on vely see a. HoweveS(t) [L0 is the initial distance between the centroid of droplet 1 and droplet 2; L represents the instantaneous distance between them at time point t. Obviously, if the two droplets merge well, the shrinkage function values will tend to 1.0. While the fusion always occurs only in the internal contact region, and atoms in the outer edge cannot move freely under the external electric field and interaction from other atoms. Thus, the shrinkage function values are always less than 1.0. f of 1.25, 5.0 and 10.0 GHz and electric field strength of 0.50, 0.60, 0.70 and cE V/nm. It should be noted that only two curves with the electric field strength E equals 0.50 and 0.59 V/nm are shown in cE is 0.59 V/nm when f is 1.25 GHz. At this case, droplet 1 and droplet 2 coalescence very well under electric field E = 0.50 V/nm, and the corresponding shrinkage function value reaches the maximum of 0.97. However, the coalescence effect comes to decrease when the electric field is E = c.E Furthermore, this phenomenon is consistent with the DC electric field [Furthermore, the centroid trajectory of the droplets during the coalescence process under electric fields can be represented by the shrinkage function, S(t) ,(3)S(t)ic field . This mi0t) gradually decreases with the increase of electric field strength, and the shrinkage function value of droplets after coalescence is closer to 1. When the E = cE, droplet 1 and droplet 2 perform best in coalescence, with the shrinkage function value of 0.91, 0.83, respectively. Moreover, the time required for contacting (0t) at 10.0 GHz is smaller than that at 5.0 GHz with the same electric field strength , indicating that the increased electric field frequency promotes the droplet movement. In the coalescence process after contacting , the corresponding shrinkage curve value when the electric field frequency f is 10.0 GHz is smaller than that at the case with f = 5.0 GHz, indicating that the increase of the electric field frequency f cannot improve the coalescence effect of the droplets. t = 200 ps.However, when the electric field frequency becomes 5.0, 10.0 GHz b,c, the E = 0.60, 0.70, 0.77 V/nm when the electric field frequency was 10 GHz. Additionally, the largest fluctuation amplitude appears under electric field of 0.77 V/nm. In this section, the dynamic deformation process of the merged droplets are taken as examples to discuss the oscillation phenomenon after convergence. f = 10.0 GHz, E = 0.77 V/nm.As discussed above, after the two droplets merged to one big droplet, the shrinkage function curve showed the same fluctuations as the electric field frequency period at − in droplet 1 and ions Na+ in droplet 2 accumulated at the opposite end under the effect of electric field while the two droplet contacting (t = 0 ps). As the two droplets are close to merge, ions Cl− tends to be further mixed to Na+ (t = 72 ps). At t = 105 ps  in t = 204, 256 and 306 ps, respectively. Clearly, the minimum value of shrinkage function become larger as the simulation, indicating a more spherical droplet is formed under this AC electric field. Thus, the merged droplet oscillate along with the AC electric field, and the coalescence effect of droplet 1 and droplet 2 gradually becomes better during the process. Subsequently, the merged droplets experience the peak, valley and peak of electric field and the corresponding shrinkage function value reaches to the minimum of 0.79, maximum of 0.85 and minimum of 0.83 at f, the critical electric field strength (cE) for droplet coalescence increase, and the corresponding time required for droplet contacting (t0) decreases. The higher the electric field frequency, the less likely the droplet deforms with the periodic change of the AC electric field . After droplets contact (t > 0 ps), the best coalescence of the two droplets occurs under the electric field with frequency of 1.25 GHz and strength of 0.50 V/nm. When the electric field frequency increases to 5.0, 10.0 GHz, the coalescence effect of the droplets shows better with the increase of electric field strength. In addition, at the electric field frequency f = 10.0 GHz, the shape of the droplet oscillates obviously after merging, which causes obvious periodic fluctuations of the shrinkage function curve. By investigating the oscillation phenomenon of droplet at E = cE, it was found that the merged droplets are stretched longer at the peak of the AC electric field, the shrinkage function value reach the minimum, while in the valley of AC electric field the large droplets tend to be spherical and the shrinkage function value increase up to the maximum. Finally, the coalescence effect becomes better and a more spherical droplet can form.In conclusion, with the increase of the electric field frequency cE increases with the increase of electric field frequency. When the AC electric field frequency is 1.25, 5.0 and 10.0 GHz, the critical electric field strength cE is 0.59, 0.70 and 0.77 V/nm, respectively. According to the analysis of the shrinkage function, under the electric field E = 0.60, 0.70, 0.80, cE V/nm, the higher the electric field frequency, the less likely the shape of the droplet is to change periodically with the AC electric field. Additionally, a nearly spherical droplet formed under electric field E = 0.50 V/nm with f = 1.25 GHz. In addition, at the cases with electric field frequency f =10.0 GHz, the shape of the droplet oscillates significantly after coalescence, and causes obvious periodic fluctuations in the shrinkage function. The presented simulation results are significant and could provide theoretical basis for the improvement of electrostatic dehydration on the molecular level.In this paper, the molecular dynamic models of two ionic nanodroplets (NaCl concentration of 0.4394 M) under the AC electric field are established to investigate the coalescence and break-up behaviors of nanodroplet, and to discuss the effect of electric field frequency and strength on the processes of droplet deformation, motion and coalescence. The results show that the time required for the two droplets contacting shows a decrease, and the critical electric field strength In this paper, the size of the two droplets is the same and nitrogen molecules are applied to represent the other phase (oil). It is better if the real oil phase could be replaced by asphaltene, resin and n-hexane. An excellent outcome may be achieved by considering these effect factors. Therefore, more studies are necessary to reveal the microscopic effect mechanism of droplet size and the real oil structure on the coalescence and break-up behaviors.


The outbreak of the COVID-19 in early 2020 and the recurring epidemic in later years have disturbed China’s economy. Moreover, China’s demographic dividend has been disappearing due to its fastest aging population and declining birth rate. The birth rates in eastern provinces of China are much lower than those of the western provinces. Considering the impacts of the COVID-19 and aging population, this paper focused on the relationship between birth rate and the disposable income and tried to find effective measures to raise China’s birth rate. We discovered through regression analysis that the link between per capita disposable income and birth rate is initially "reverse J" and later "inverted J", indicating that per capita disposable income will influence the birth rate. Women’s employment rate and educational level are negatively correlated with the birth rate. To raise the fertility rate in China, it is necessary to increase the marriage rate and the willingness to have children by raising the per capita disposable income and introducing effective tax relief policies. The outbreak of the COVID-19 in China in early 2020 hindered China’s economic development and there are sporadic reports to date of COVID-19 recurrence. [According to the 7th census statistics, China’s total fertility rate in 2020 stood at 1.3, which was below the international birth alert line. "Chinese population was older and consisted of fewer children". The declining newborn birth rate, increasing mortality rate and aging population will hinder China’s economic development. To address this problem, the Political Bureau meeting of the CPC Central Committee proposed to implement a three-child policy with supportive measures to increase the birth rate and promote a balanced population [By analyzing the population aged over 60 and under 14 in China, Chen . Tax refAccording to Chia and Li, increasing income tax relief for children’s educational expenses and adding deductions for childbirth, childcare, and parenting special children can reduce the financial strain of childbearing families, increase disposable income, and raise the birth rate . AccordiPeng and Cheng empirically studied the relationship between fertility and personal income tax and found that the tax value of the personal exemption would increase the general fertility rate . Liu andIn summary, the improvement of the birth rate, which is an important topic in China, has gained much attention from researchers. The birth rate is closely related to the residents’ willingness to have children, which is influenced by a variety factors, such as household disposable income, childbirth costs, gender of the newborn, women’s educational level, employment, etc. At present, most studies regard the birth rate and per capita disposable income as separate subjects. There hasn’t been much research done on their relationship. As fast aging population in China and the low birth rate can be affected by the COVID-19, this paper explores the relationship between birth rate and per capita disposable income, as well as the per capita disposable income and birth rate in the central, western, eastern and northeastern regions. What’s more, this study has proposed several measures to improve the birth rate, including reducing costs of housing, education, and medical care, increasing the marriage rate and willingness to have children, and introducing preferential policies for childbirth. China’s three north-eastern provinces—Heilongjiang, Jilin and Liaoning, among others, need to be paid special attention to stabilize the birth rate.According to the data of China National Bureau of Statistics, the growth rate of Chinese population is low in the past 10 years. From 2000 to 2010, the birth rate keeps falling . This paper uses the birth rate of Chinese population to represent the birth rate, and the data are obtained from the National Bureau of Statistics.Explanatory variable: per capita disposable income (PCDI). From the relationship between birth rate and per capita disposable income , we can (1) Marriage rate (MR): An increase in the marriage rate will, to a certain extent, promote the birth rate. Therefore, the marriage rate is selected as the control variable. The data are obtained from the World Bank and the China National Bureau of Statistics.(2) Female employment rate (FER): Higher the female employment rate will reduce the willingness of women to have children, and thus lower the birth rate. Many companies believe that if women get pregnancy and give birth to babies, their working productivity may decrease. So, they may refuse to hire women if they choose to have children. Losing employment becomes a hidden cost of childbirth for women. To secure their employment opportunities, women may choose to have children later, less or no children. Therefore, this study selects female employment rate as the control variable. The data are obtained from OECD database.(3) Educational attainment (EL): this study adopts the percentage of family members with college degree or above as the measure of educational attainment. According to the questionnaire survey, families with higher education attainment have lower fertility intention and the birth rate. Therefore, the educational attainment is selected as the control variable. Related data are obtained from the World Bank database.(4) Fertility intention (BP): fertility intention can significantly affect birth rate. we have collected relevant data through a questionnaire survey, in which 1 stands for families willing to have children, and 0 means those who are unwilling to have children.Control variablesAccording to 2 is 6.73e-06 when the squared per capita disposable income term and control variables are included in (4), and the results of (4) show that the per capita disposable income at the turning point is RMB 12,520 and RMB 20,167. They are within the range of the values in the sample. Therefore, the relationship between per capita disposable income and birth rate follows an "inverse J" and "inverted J" patterns.This study selected the panel data of China from 1980–2021 and adopted stata17.0 software to estimate the benchmark regression model. The vif covariance test was performed on equations (3) and (4) of For the robustness test, we changed the explanatory variables. To further test the relationship between birth rate and disposable income per capita, we performed the regression analysis on the logarithm of the explanatory variable disposable income per capita. China’s current birth rate is low. Moreover, the imbalance of the economic development in China results in a huge gap in the birth rate between the east and west. The birth rate in the eastern region is lower than the west. Through the comparison of birth rates in different provinces, we found that the birth rate in Yunnan and Guizhou has been maintained at more than 1.2%, mainly because the local ethnic minorities account for a larger proportion of the population, and China has preferential policy for them. The birth rates in Beijing and Shanghai have been declining over the past 5 years, and the birth rates in 2021 were only 0.635% and 0.467%. As first-tier cities, Beijing and Shanghai have more developed economies. Young people in Beijing and Shanghai have higher educational attainment, and their living, housing, childcare costs are very high. Under such pressure, they are less likely to have many children. The three northeastern provinces, especially Heilongjiang province, of which the birth rate was only 0.359% in 2021, have much lower birth rates than the national average. Due to the outflow of population, the birth rates of this region stay at the bottom of the country. For the first-tier cities, China should introduce more family-friendly policies, such as subsidies, allowances, tax breaks, maternity insurance to reduce the cost of living in these regions. For the three northeastern provinces, the government need to prevent the outflow of population by increasing both the number of jobs and the productivity as well as incomes from employment of this regions.According to the empirical analysis, the relationship between per capita disposable income and birth rate is first "inverse J" and then "inverted J", indicating that increasing per capita disposable income will have some effect on birth rates. Women’s employment rate and education level are negatively related to birth rates, but the marriage rate and fertility intention are positively correlated with birth rates. To increase birth rates, China should lower the living costs and increase per capita disposable income. Expenditures in housing, education and medical care make for a relatively substantial share of residential spending. Therefore, to reduce the living cost of residents, we should first focus on housing, education and medical costs and on top of that China should also boost the marriage rate and fertility intentions to improve the birth rate.China should issue more policies and tax relief to increase birth rate. Our recommendations are as follows:Child allowances are a major incentive to encourage childbirth and solve families’ financial difficulties. In Russia, there is a policy that provides for a one-time financial allowance for each newborn baby, equivalent to 2.6 times the country’s average annual wage. In Germany, parental allowance is a minimum of 300 euros and a maximum of 1,800 euros monthly. In Japan, women being four months pregnant are entitled to a variety of benefits. To reduce the financial burden of childbirth for families, the government will also provide a subsidy of ¥100,000 for every newborn. Like other countries, China should also increase the types and amounts of allowances to complement maternity insurance. Moreover, the government should provide additional benefits to families or encourage companies to hire more women by providing incentives for such hiring.As the economy develops and education levels increase, parents have higher expectations for their children and invest more in education. In Germany, parents can make a tax deduction on their income based on their children’s education; in the United States, some education expenses are tax deductible or may allow taxpayers to claim a tax credit. For French residents, the deduction varies according to the age and education stages of the child. China should increase the pre-tax deduction for children’s education. Currently, for children’s education, an amount of 1,000 yuan ($145) will be deducted every month from the parents’ taxable income for each child’s education. However, the educational costs are more expensive in China. Therefore, the government should consider to increase deduction amount to compensate the parents.The use of childcare has become increasingly common. Such care is essential for families where both parents work outside the home, and many other families choose to place their children in childcare in an effort to better prepare them for school. Many countries provide deductions associated with childcare. For example, in Germany, parents can deduct up to 4000€ in services related to childcare, when hiring nurses or going to a child care center, etc. The provision of childcare facilities in France relaxes the parents’ time constraints and alleviates the parental burden in terms of childcare. In China, a growing share of families are unwilling to give birth, because childbirth is expensive and they do not have the help from family relatives, particularly grandparents, to take care of their children. To address this issue, China should increase its child care capacity, while provide tax benefits to offset child care costs, such as the child care tax credit.In recent years, families’ spending on children’s health care, from infancy to early childhood, has risen considerably. To ease the financial pressures for new parents, many governments have enacted health-care policies for children. In Germany, parents can make tax savings by deducting their expenses for all medical expenses of their children; Russia introduced income tax deductions for children’s medical expenses, including medical expenses for children under 18 years old, and life insurance or supplementary medical insurance premiums for children over 5 years old. Currently, Chines residents can only deduct the medical cost that is over RMB 15,000 and borne by the individuals, but such deduction does not cover the medical expenses of their children. To free parents from the financial cost of childbirth, the government needs to cover this part and increase the deduction for children’s medical expenses.Chinese residents are facing sky-high mortgage and housing prices, especially for the “the school district houses”. The policy of “nearby enrollment” was enacted to equalize the opportunities for students to enter schools, narrow the gap between key schools and weaker schools. However, most families want to invest more in each child to give them the best opportunities to compete in an increasingly unequal environment. The actual outcome of the mania for “school district house” was that the price of housing around better schools increased. China should reduce mortgage interest, offer housing and rental subsidies or tax incentives, and increase its investment in education. The government need to decouple property and education by delinking students’ educational options from their residential addresses, thus reducing housing and education costs.At present, China’s marriage rate is reduced. Men and women with higher educational attainment tend to pursue better life quality. They set a high bar in the hopes of finding the perfect partner, resulting in a growing numbers of single population. In China, the legal age for marriage of men and women is 22 and 20 years old, respectively. In most developed countries, the legal age for marriage is 18 years old. Under special circumstances, it can be lowered to 16 years old. To increase the birth rate, China can lower the legal age of marriage. Meanwhile, it can lower the divorce rate by providing family therapy or extending the divorce cooling-off period. In addition, for couples who are willing to have children, they can be exempted from the marriage restriction and the society should provide parents basic childcare support and preferential policies, so that to increase fertility intentions and birth rates.S1 Data(XLS)Click here for additional data file.