Electric upsetting has been widely employed to manufacture the preformed workpiece of large-scale exhaust valves. The temperature field in the electric upsetting process plays an important role in microstructure evolution and defect formation. In order to uncover the temperature evolution in a larger-scale electric upsetting process, the electric-thermal-mechanical multi-field coupling finite element model was developed to simulate the electric upsetting forming process of Ni80A superalloy. The temperature distribution characteristics and their formation mechanisms under different stages were analyzed systematically. Results indicate that at the preheating stage, the billet temperature increases from 20 °C to 516.7 °C, and the higher temperature region firstly appears at the contact surface between billet and anvil due to the combined effects of contact resistance and volume resistance. With increasing preheating time, the higher temperature region is transferred to the interior of the billet because the contact resistance is reduced with increasing temperature. As for the forming process, the billet is gradually deformed into an onion shape. The highest billet temperature increases to 1150 °C and keeps relatively constant. The high temperature region always appears at the neck of the onion due to the relatively higher current density at this place. It enlarges continuously in the primary stage and intermediate stage, and then decreases at the stable deformation stage. The low temperature regions lie in the contact surface and the outer surface of the onion because a lot of heat is lost to the anvil and surroundings through thermal conduction and radiation. Finally, the established finite element model was verified by an actual electric upsetting experiment. The average relative error between simulated temperatures and experimental ones was estimated as 7.54%. The longitudinal and radial errors between simulated onion shape and the experimental one were calculated as 1.38% and 2.70%, respectively. Nickel-based alloys have been extensively applied in aviation engines, turbines and marine diesel engines in virtue of their superior strength and strong creep resistance at elevated service temperature ,2. As a In a certain electric upsetting process, a long-rod billet is sandwiched between an anvil electrode and an upsetting cylinder, and the stem of the billet is clamped by a pair of clamping electrodes. A low-voltage and high-amperage direct current with step change is loaded on the anvil, and the clamping electrodes are grounded. For the large-scale electric upsetting process, the approximate values of voltage and amperage are 5 V and 20 KA, respectively. In addition, an insulation spacer is placed between the billet and the upsetting cylinder. Thus, the current will flow from the anvil to the billet, and then to the clamping electrodes. The part of the billet with current flowing will be heated by self-resistance and contact resistance. An upsetting force with step change is loaded on the right end surface of the billet by the upsetting cylinder. Under the coupling effects of upsetting force and heating current, that portion of the billet is heated locally and begins to enlarge. Meanwhile, the anvil electrode retreats with a specific speed to make space for the deformed billet. As this process continues, a large portion of the billet material will be formed into a desirable shape.It is well known that the properties of an exhaust valve mainly depend on its microstructures, which to a great extent are determined by the grain size in the electric upsetting process ,10. The Nevertheless, the electric upsetting process is essentially a complicated electric-thermal-mechanical multi-field coupling issue, in which various thermal-related mechanisms involving electric heating, heat transfer and thermal radiation coexist. It is extremely difficult to directly observe and predict the temperature field evolution in a practical electric upsetting process. The finite element simulation method (FEM) provides a solution. It can not only consider the coupling effects of an electric-thermal-mechanical multi-field, but also reveal the dynamic evolution process of the temperature field in temporal and spacial domains ,16. BibaIn this work, a FEM model of a large-scale electric upsetting process was developed, in which a series of thermal-related behaviors involving electric heating, thermal conduction and thermal radiation were taken into account. The distribution and evolution of the temperature field at different stages of the large-scale electric upsetting process of Ni80A superalloy were uncovered. The location and size of the high temperature region were analyzed, and the formation mechanisms of such temperature distribution characteristics were discussed in detail. Finally, the established FEM model was verified by an actual electric upsetting experiment.V represents voltage, I is current and EK(T) represents the electric conductivity dependent on temperature; EQ represents Joule heat. TK(T) and TC(T) represent the temperature-dependent thermal conductivity and specific heat, respectively; T, u and t represent temperature vector, displacement vector and time, respectively; PQ represents the heat from plastic work; FQ represents the heat generated by friction; LQ represents the heat loss;. M is mass matrix; D represents damping coefficient; MK represents stiffness matrix; and F and TF represent external force and thermal stress, respectively.Electric upsetting can be regarded as a current-heating forming process, involving electric heating, heat conduction and thermal-plastic deformation. The finite element simulation of an electric upsetting process can be treated as an electric-thermal-mechanical multi-field coupling problem. It can be realized on many commercial finite-element simulation platforms, such as Deform, Marc, Qform, etc. In order to develop the electric-upsetting FEM model, it is necessary to grasp the complex interactions between electric, thermal and mechanical fields, and then establish quantitative equations to describe them. Here, the coupling relationships among the three fields are schematically described in EQ is shown as Equation (2) [nI represents the nodal current going through the contact surface and billet; VR and CR represent the volume-resistance of the billet, and the contact-resistance between billet and anvils, respectively; and ka and kb represent the heat conductivity values of anvil and billet, respectively.It must be pointed out that the resistance heat consists of two parts. One is volume-resistance heating, and the other comes from contact-resistance between billet and anvil. Both of them follow Joule’s law. The Joule heat generated by contact resistance is conducted to the billet and anvil proportionally to their heat conductivity. Then, the final expression of Joule heat tion (2) ,(2){QE=β represents the conversion rate of plastic work to heat, The heat generation owing to plastic work can be estimated by Equation (3) ,(3)Qp=βu represent the friction coefficient, and The heat generated by friction can be calculated by Equation (4) ,(4)QF=∫hc and hs represent the heat conduction coefficient; f is thermal radiation coefficient; cA is the area of contact surface; sA is the area exposed to surroundings; sA is the heat radiation area on the billet; and bT, aT and sT represent the temperatures of billet, anvil and surroundings, respectively.Furthermore, the heat loss due to heat conduction and thermal radiation can be expressed as Equation (5) ,(5){QL=For a given electric-thermal-mechanical multi-field coupling analysis, the electric field, thermal field and mechanical field will be solved in turn. All of these matrix equations will be iterated many times until convergence. The computing procedures can be schematically described as in Based on the solving procedures of electric-thermal-mechanical multi-field coupling analysis, the FEM model of electric upsetting can be developed on the solving platform MSC marc. Here, a half-symmetry 2D finite element model was constructed, as shown in By following the design principles of parameter loading path mentioned in our previous work , the upsAccording to the characteristics of parameter loading path, as in In the present electric upsetting FEM simulation, the preheating time was set as 30 s; and the range of two steps before and after the peak current and force was defined as the intermediate stage of the forming process. The approximate upsetting displacement boundaries for separating the three stages in the forming process are 155 mm and 325 mm according to the parameter loading path diagram. On the other hand, it was found from the numerical simulation results that the electric upsetting time of 350 s and 550 s correspond to the upsetting displacement of 156 mm and 326 mm, respectively. Therefore, for the sake of description, the beginning and end of stage (iii) were specified as 350 s and 550 s. In addition, in this work, the preheating stage, primary stage, intermediate stage, and stable deformation stage are defined as the following four electric upsetting periods:(i) 0~30 s, (ii) 30~350 s, (iii) 350~550 s and (iv) 550~2000 s (the end of the electric upsetting process). A detailed discussion on the temperature field evolution in the four stages will be presented in the following Sections.In the first thirty seconds of the electric upsetting process, the anvil remains stationary to ensure the billet is preheated adequately. In order to analyze the interior mechanisms that cause such temperature distribution, the highest billet temperature and the nodal temperature on the contact surface varying with preheating time were extracted and plotted in R = 1/(a1T + a2), where T is the temperature, and a1 and a2 are the constants dependent on contact pressure, here 0.87 and 132, respectively. With that, the variation of contact resistance along with preheating time can be exhibited, as in Since most heat in the billet comes from electric heating, it is necessary to analyze its current density distribution and electric resistance variation. According to reference , the conThe evolution of the highest overall temperature and of the contact surface temperature during the primary stage of the forming process is shown in Furthermore, the current density evolution in the electric upsetting process was analyzed. The current density distributions at different moments during the primary stage are presented in The distributions of the temperature field at different moments in the intermediate stage of the forming process are displayed in S. Its calculation method can be expressed as Equation (6),iS represents the area of every element, and n is the number of the elements whose temperature is in the specific range. In this work, the element whose temperature exceeds 500 °C will be identified as representing the onion, while the element whose temperature exceeds 1085 °C will be regarded as representing the high temperature region, and the rest are billet stem elements. The temperature of each element can be estimated using the average value of its four integration point temperatures. Based on the calculation formula, the areas of high temperature region and onion corresponding to the electric upsetting time of 400 s, 450 s, 500 s and 550 s were calculated and revealed in According to our previous investigation, the high temperature region has significant influence on grain growth, and even determines the mechanical properties of the formed workpiece. In order to quantitatively describe the evolution of the high temperature region, the area of high temperature region was evaluated using an indicator According to the above analysis, an interesting phenomenon is that the highest temperature remains basically unchanged, while the high temperature region grows continuously. This result can be explained by the following reasons. During the intermediate stage of the electric upsetting, the astern speed of the anvil is constant, and the variations of heating current and upsetting force are small, so that the electric upsetting system is always in equilibrium. Correspondingly, the highest temperature remains relatively constant. As for the size of the high temperature region, this is closely associated with the current density distribution of the billet. Here, the current density distributions of the billet corresponding to the electric upsetting time of 400 s, 450 s, 500 s and 550 s are presented in X-axis in In order to quantitatively analyze the temperature distribution during the stable deformation stage, the evolution of maximum temperature and of contact surface temperature with respect to electric upsetting time were extracted and are presented in For the sake of analyzing the evolution of the high temperature region, the area of high temperature region and the area of the deformation region (area of the onion) at the electric upsetting moments of 750 s, 1000 s, 1250 s, 1500 s, 1750 s and 2000 s were counted and shown in In order to clarify the formation mechanisms of these temperature distributions in the stable deformation stage, the heat flux distribution of the billet is presented in In order to verify the established electric-thermal-mechanical multi-field coupling electric upsetting FEM model, a practical electric upsetting experiment was conducted on an electric upsetting machine using the loading parameters exhibited in Both of the temperature data obtained from the electric upsetting experiment and from the finite element simulation were plotted in ARE represents the average relative error; n is the number of recorded temperature data. For the preheating stage, n is 7; for the forming process, n is 36. Therefore, the finial ARE-value of the electric upsetting process is calculated as 7.54%. According to the comparison of simulated temperature data and experimental ones in In order to justify the accuracy of the established electric upsetting FEM model, the average relative error between simulated temperature data and experimental ones will be evaluated by Equation (7),In this work, an electric-thermal-mechanical multi-field coupling FEM model was established to simulate the electric upsetting process. The distribution characteristics of the temperature field in different stages of the electric upsetting process, and the field formation mechanisms, were analyzed in detail. This work provides a thorough insight into the temperature evolution in the electric upsetting process. It contributes to future work on predicting the microstructure evolution and analyzing the defect formation during the electric upsetting process. Moreover, it offers an important guidance for future work on finding an appropriate method to adjust the temperature distribution in electric upsetting. Several conclusions can be drawn from this work as follows.(1)During the preheating process, the higher temperature firstly appears at the contact surface between anvil and billet due to the combined effects of contact resistance and volume resistance. With increasing preheating time, the higher temperature is transferred to the interior of the billet because the effect of contact resistance weakens with increasing temperature.(2)For the primary stage of the forming process, the high temperature region is transferred from the interior of the billet to the neck of the onion, and an obvious low temperature region emerges at the contact surface between anvil and billet because the effect of heat transfer between anvil and billet is enhanced under the elevated temperature, and the relatively higher current density concentrates in the neck of the onion.(3)In the intermediate stage of the forming process, the high temperature region always appears at the neck of the onion, and the lower temperature region is at the contact surface. In addition, the area and proportion of high temperature region both increase as the electric upsetting process proceeds, which is attributed to the increasingly homogenous current density distribution.(4)As for the stable deformation stage of the electric upsetting process, the high temperature region still appears at the neck of the onion, and the low temperature regions lie in the contact surface and the outer surface of the onion owing to the heat transfer between anvil and billet, thermal radiation on the outer surface of the billet, and thermal dispersion to the billet stem, as well as abundant Joule heat generated at the neck of the onion.


A meningocele is a congenital neural tube defect, and the majority of the meningocele cases are identified perinatally. We present the case of a 67-year-old patient with a sacral meningocele undiagnosed until the removal of a symptomatic epidermal inclusion cyst adjacent to it. Cerebrospinal fluid leakage occurred due to an incision in an undiagnosed meningocele adjacent to the epidermal inclusion cyst. Repair of the cerebrospinal fluid leakage was performed successfully without any deficit. The present case underscores the importance of considering a meningocele as a differential diagnosis for a mass occurring in the midline of the back at any age. Meningocele is an uncommon neural tube closure defect characterized by the protrusion of a spinal fluid-filled sac lined by meninges through the posterior spina bifida without neural tissue herniation . The majEpidermal inclusion cysts are harmless, slow-growing bumps under the skin that commonly occur on the face, neck, upper back, scrotum, and genitals although they can occur anywhere. Epidermal inclusion cysts are more frequent in adulthood .Here, we present the case of an elderly patient with a sacral meningocele diagnosed during the removal of a symptomatic epidermal inclusion cyst. Cerebrospinal fluid (CSF) leakage occurred due to an incision in an undiagnosed meningocele adjacent to the epidermal inclusion cyst. Repair of the CSF leakage was performed successfully without any deficit. A meningocele should be considered a differential diagnosis of cysts in the dorsal midline of the body, particularly the buttocks, even in adults.A 67-year-old male without any developmental problems presented with a subcutaneous mass in the buttock Figure . He had As the leakage persisted, the patient was referred to our hospital the day after the surgery. Fluid leakage was observed from only the cranial incision on the midline cyst and not from the caudal cyst Figure . LumbosaThe histological findings of the paramedian caudal cyst resected at the first surgery by the local dermatologist showed granulation tissue and keratin material, suggesting an epidermal inclusion cyst Figure , 4B. HowA meningocele is the simplest form of an open neural tube defect, and it accounts for 2.4% of closed spinal dysraphism cases . The majIn the present case, an epidermal inclusion cyst existed adjacent to an undiagnosed sacral meningocele. Epidermal inclusion cysts occur anywhere in the body, and the buttock is one of the most common sites. Although a meningocele is extremely rare in the elderly, as described above, the possibility of encountering a meningocele should be considered in differential diagnoses of an epidermal inclusion cyst in the buttock.Many cases with an epidermal inclusion cyst tend to be treated by an office surgeon or dermatologist. However, the incision of a meningocele will lead to CSF leakage. Because CSF leakage can lead to severe sequelae such as meningitis, subdural hematoma, and cerebral venous thrombosis ,10, corrIn many cases, ultrasound scanning is useful to differentiate the meningocele from an epidermal inclusion cyst. Since a meningocele contains CSF, it appears as a uniform low-echoic cyst. In contrast, an epidermal inclusion cyst generally exhibits inner echogenicity, reflecting debris , and neaGenerally, CT or MRI is required to diagnose an epidermal inclusion cyst with a nonspecific appearance . HoweverWe encountered a rare case in which an epidermal inclusion cyst occurred adjacent to a sacral meningocele with a delayed presentation in an elderly person. A meningocele can be present at any age, and it should be considered as a differential diagnosis of a cyst in the dorsal midline of the body in both children and adults. In particular, surgical treatment should be performed only if the absence of spinal meningeal cysts involving CSF or neural tissue can be ruled out.


Associations between birth weight (BW) and adult lung function have been inconsistent and limited to early adulthood. We aimed to study this association in two population-based cohorts and explore if BW, adjusted for gestational age, predicts adult lung function. We also tested adult lung function impairment according to the mis-match hypothesis—small babies growing big as adults.We included 3495 individuals (aged 46.4 ± 5.4 years) from the Malmo Preventive Project (MPP), Sweden, born between 1921 and 1949, and 1401 young to middle-aged individuals (aged 28.6 ± 6.7 years) from the Malmo Offspring Study (MOS) with complete data on BW and gestational age. Adult lung function  were analysed as level of impairment (z-score), using multiple linear and logistic regressions.BW (z-score) did not predict adult lung function in MPP, whereas BW was a significant (p = 0.003) predictor of FEV1 following full adjustment in MOS. For every additional unit increase in BW, children were 0.77 (95% CI 0.65–0.92) times less likely to have impaired adult lung function (FEV1). Moreover, adults born with lower BW (< 3510 g) showed improved lung function  if they achieved higher adult body weight.Adults born with lower birth weight, adjusted for gestational age, are more likely to have impaired lung function, seen in a younger birth cohort. Postnatal growth pattern may, however, compensate for low birth weight and contribute to better adult lung function.The online version contains supplementary material available at 10.1186/s12931-022-02269-2. Growing evidence indicates that early life events and growth are important for later lung health irrespective of smoking habits, which in itself is a well-known risk factor affecting lung health –4. A sysAccording to the DOHaD  concept, a fetus can undergo both adaptive and non-adaptive responses to changes in the intrauterine environment and thereby persistently alter physiological homeostasis that may influence the long-term risk of disease –8. The pIntrauterine growth restriction (IUGR) that can be caused by maternal, placental, fetal and/or environmental factors, may have a negative impact on lung development and adult lung function , 9, 10. Data on birth weight and adult lung function are limited; studies are mostly restricted to adolescence and early adulthood , 15–17, aimed to examine the association between birth weight, adjusted for gestational age, and lung function in adult life in two separate population-based projects in both men and women; the Malmo Preventive Project (MPP) in older and the Malmo Offspring Study (MOS) in younger subjects. Our hypothesis was that low birth weight or specific post-natal growth patterns could be associated with adult lung function.This observational study “Are you a smoker?” (yes/no). Level of education was also obtained through a questionnaire. Questions were “Have you completed elementary school (folkskola), primary school or similar?”, “Have you completed junior secondary school , vocational school or similar?” and “Have you completed secondary school, folk high-school (= adult education centre) or similar?” with answer options “yes”, or “no”.MPP is a large population-based cohort that started in 1974, inviting mostly middle-aged men and women residing in the city of Malmo, Sweden, with a participation rate of over 70% . A total1). The manoeuvre was performed with the individual in an upright standing position without a nose clip. More details on lung function testing and the measurement of pulmonary function have been previously published [A total of 28,934 individuals underwent spirometry using a Spirotron apparatus , performed by specially trained nurses, including values for peak flow, forced vital capacity (FVC), and forced expiratory volume in one second  were collected from local hospital archives in southern Sweden, available for 4359 individuals (3883 men and 476 women), derived from two nested case–control studies aimed to study risk on breast- or prostate cancer , 26. For2) was calculated. Smoking history and level of education were obtained through a questionnaire. One of the questions regarding smoking was “Do you smoke?” with answer options “yes, I smoke regularly”, “yes, I smoke occasionally”, “no, I have stopped” or “no, I have never smoked”. Furthermore, participants were asked to tick the option that corresponds to the highest level of education they had completed.MOS is an ongoing population-based cohort since 2013 (attendance rate 47%) that invites adult children and grandchildren of participants in the Malmo Diet Cancer-Cardiovascular Arm (MDC-CV) study . Partici1. The spirometry maneuver was performed in accordance with guidelines from ATS/ERS [1 were used.Screening spirometry was performed by specially trained nurses using a MasterScope spirometer  with the individual standing with a nose clip providing values for FVC and FEV ATS/ERS . The higBirth parameters for the study participants were obtained from the Swedish Medical Birth Register (MBR) starting in 1973. A personal 10-digit identity number, unique for every Swedish citizen, was used to link the MOS data collected at the health examination with the MBR data. Birth weight (gram) was available for 1401 (born 1973 or later) out of 3200 participants, see Additional file Statistical analysis was performed using IBM SPSS statistics for windows version 25.0 . The average for all continuous variables was described as the mean and standard deviation (SD). The distribution of categorical variables was expressed as percentages. An independent-samples t-test was conducted to compare the means of continuous variables for men and women. A two-tailed p < 0.05 was taken to indicate statistical significance.1, FVC, FEV1/FVC-ratio) and birth weight were standardized as z-scores based on GLI [The predicted lung function values were calculated using The Global Lung Function Initiative (GLI) reference values . Absolutd on GLI  and Marsd on GLI  normal rd on GLI .Covariates (confounders) to include in the models were selected based on the literature and current knowledge in the field using a causal diagram (DAGitty software) , shown iSelected covariates (confounders) to adjust for in the final models were offspring’s educational level and smoking status, whereas gestational age, sex, height, age and ethnicity are variables that have already been taken into account when calculating z-scores.Linear regression models were conducted in a structured, step-wise approach:Firstly, a univariate linear regression was computed to assess the association between each of the birth parameters  and lung function in adult life (expressed as z-score) in the total population.Secondly, hierarchical multiple regression and mixed linear model analysis accounting for clustering between siblings was used to assess the ability of birth weight deviations to predict lung function deviations in adult life using birth weight (z-score) as independent variable and FEV1, FVC and FEV1/FVC-ratio as continuous, dependent variables, respectively. First analysis was run unadjusted (Model 0). Offspring’s educational level was entered in Model 1 while the offspring’s smoking status was added to Model 2.1, FVC and FEV1/FVC-ratio as categorical dependent variable, respectively. Further adjustments for potential covariates were made in two models. In Model 1, adjustment was made for offspring’s educational level while in Model 2, adjustment for offspring’s smoking habits was added.Then, logistic regression was performed to calculate the odds ratio (OR) for having impaired lung function in adult life  using birth weight (z-score) as an independent variable and FEVFurthermore, a two-way between-groups analysis of variance (ANOVA) was conducted to explore the impact of birth weight and achieved adult weight on lung function transformed to z-score. Birth weight  and weight in adult life were divided into two categories: high and low, with medians as cut-offs: 3510 g (g) and 74 kg, respectively. Participants were then stratified into four groups .The general characteristics of the study populations are presented for MPP Table  and for Of the 3495 participants, 3330 (95.2%) were men and 165 (4.8%) women (by study design). Nearly 79% of participants had birth weights within the normal range (2500–4000 g). Of the remaining subjects, 3.5% had low birth weight (< 2500 g) and 18% had high birth weight (> 4000 g), which is representative compared to the national average for Sweden .As shown in Table 1, FVC and FEV1/FVC between genders, with women showing lower spirometry values compared to men (p < 0.001) in both MPP and MOS.Of the 1401 participants, 672 (48%) were men and 729 (52%) women. Nearly 78% of participants were born within the normal birth weight range (2500–4000 g). Of the remaining subjects, 5.5% had low birth weight (< 2500 g) and 16.5% had high birth weight (> 4000 g). The mean (± SD) age at MOS baseline screening was 28.8 (± 6.8) years for men and 28.3 (± 6.5) for women. Of the 1401 participants, 704 (50.2%) were siblings. Additional file As shown in Additional file 1 (z-score) , but not when adjusted for offspring’s educational level and smoking status. Also, the mixed linear model accounting for clustering showed that birth weight deviation was not a statistically significant predictor of lung function in adult life after adjustment for offspring’s educational level and smoking status  as an independent variable and each z-score of adult lung function as the dependent variable are shown in Additional file 1 even after adjustment for the offspring’s educational level and smoking status. Thus, for every additional unit (deviation) in birth weight, the odds of offspring having low FEV1 were 0.77 times less likely. Correspondingly, an increase in birth weight resulted in a decreased probability of having low FEV1, i.e. a better lung function.Direct logistic regression was performed to assess the impact of birth weight (z-score) on the likelihood of having impaired lung function in adult age Table . In MPP,The relationship between postnatal growth patterns and lung function in adult age has been shown in Table 1 (z-score) for the group 1  − 0.98, SD 1.15) was significantly different from the means of both the group 2  and group 4 , as shown in Table group 1  and group 2 , while no statistically significant difference was observed for the mean FEV1/FVC-ratio.In MPP, group comparisons indicated that the mean FEV1 and mean FVC  was significantly different from the means of both the group 2  and group 4 , respectively.In MOS, there were no statistically significant differences between groups regarding mean FEVVC Table . However1 in the unadjusted model using multiple regression using continuous variable, but once we adjusted for offspring’s smoking habits and educational level, birth weight did not independently predict FEV1 anymore (p = 0.06). However, in the logistic regression analysis of birth weight and low FEV1, a category defined by a value lower than lower limits of normal (LLN), results remained statistically significant even after adjustment for offspring’s smoking and education. This indicates that offspring born with lower birth weight had 1.3 times increased odds of having a clinically important lung function impairment.In this prospective observational study, we investigated whether birth weight (z-score) is associated with impaired lung function (z-score) in adult life in two population-based cohorts, differing by age range but from the same population. Birth weight deviations were not an independent predictor of adult lung function in the elderly cohort—the Malmo Preventive Project (MPP). On the contrary, we found positive associations between birth weight and adult lung function in the younger cohort—the Malmo Offspring Study (MOS). In MOS, birth weight was a statistically significant predictor of FEVIn MOS, we also performed the mixed linear model analysis to explore if birth weight can predict the lung function in adult age accounting for clustering of siblings as 50% of our participants in MOS had at least one sibling enrolled in the study. The mixed linear model analysis accounting for clustering showed that birth weight deviation was not a statistically significant predictor of lung function in adult life after adjustment for offspring’s educational level and smoking status. This finding was consistent with the results from the main hierarchical multivariate regression analysis. We also tried to perform the logistic regression  accounting for clustering of siblings, but due to few participants (n < 200) having impaired lung function in adult life , a negative Hessian matrix indicated that the model was not robust and, thus, was not reported.1 and FVC at the age of 31 years increased linearly with higher birth weight [1 nor FVC were associated with birth weight in the fully adjusted models , except for FVC at the age of 53 years [1 and FVC values at 10-years of age [Previous studies on birth weight and lung function have been conflicting, with some reporting associations , 33–42, h weight . Moreove53 years . A limits of age .Similarly, a study from Hong Kong among 3030 children, showed that lower birth weight was associated with poorer lung function at 17.5 years of age, particularly in boys . Further1) was higher in children born with higher birth weight and who achieved a higher adult body weight (group 2), but also in children of lower birth weight achieving higher adult body weight (group 4), as compared to children with lower birth weight in combination with lower adult body weight (group 1). In addition, mean FVC was also higher in subjects with high birth weight achieving a higher adult body weight (group 2) compared to babies born with lower weight who stayed within a lower adult body weight (group 1). These findings might be explained by anatomical aspects of wider bronchi and increased lung volumes in people with larger bodies.Postnatal growth patterns may compensate for low birth weight and contribute to better adult lung function. Comparisons between MPP subgroups indicated that adult lung function  compared to those born with low weight who stayed within the low adult weight category (group 1).However, in MOS, no difference in mean FEVBody mass index and adiposity growth during childhood for predicting young adult asthma has been studied previously . The misThe discrepancy in our findings between MPP and MOS may be explained by cohort differences that may reflect selection bias or birth cohort effect . DiffereLimitations of the present study include the lack of information on maternal smoking during pregnancy, as well as data on lung diseases in childhood. Also, we have been restricted by a small sample size in the final analysis due to missing data on birth parameters  and spirometry results for more than half of the population from the original cohort. The degree of attendance in MOS in general is 47%. MOS consists of children and grandchildren to the index-participants in the MDCS Cardiovascular Arm with 47% attendance rate in general . Birth dThe major strengths of this study include the cohort study design and the long follow-up time. Lung function was assessed at a mean age of 46 and 28 years in MPP and MOS, respectively. Moreover, these cohorts offer objective birth register-based data, as well as information on gestational age based on medical archives or national registers. Until now, there are few cohorts providing information on both objective birth weight adjusted for gestational age and adult lung function test. An additional important strength is that we analyzed lung function measurements transformed into z-scores. Absolute lung function measurements reflect lung size which depends on several factors, such as body size, dimensions of the thoracic cavity, sex and age. The z-score takes into account age, sex, height and ethnic group and thereby minimizes the age- and height-related bias, thus enabling the comparison of lung function between individuals, irrespective of their age, sex, height, or ethnicity . FinallyIn summary, we report that babies born with lower birth weight, adjusted for gestational age, are more likely to have impaired lung function in adult life—a finding more visible in a younger and more recent birth cohort. This association is relatively weak and could have been taken over by other factors acting in adult life, such as smoking and educational level, closer to the spirometry examination. A difference may exist between generations, not just because of the time interval, but because of lifestyle changes (smoking habits) and historical developments in Sweden. Finally, we would like to underline the importance of postnatal growth patterns that may compensate for low birth weight and contribute to better adult lung function. Such a mis-match seems to be of benefit for adult lung function, as contrary to the increased risk of adult cardiometabolic disorders , 55. TheThe clinical application of the findings is not immediate as this is not a clinical study per se involving patients, but a population-based epidemiological study. However, the data add to a growing interest in clinical lung medicine to better understand the early life origins and modifiers of adult lung function. This could increase the interest in early prevention of lung disorders when healthy pregnancies and normal birth outcomes could be of importance, as well as healthy weight trajectories in childhood and adolescence.Additional file 1: Table S1. Descriptive statistics among MOS siblings and non-siblings.Table S2. Associations between birth parameters and lung function in MPP and MOS. Table S3. Birth weight for prediction of lung function in MPP and MOS. Table S4. Birth weight for prediction of lung function accounting for MOS siblings.Additional file 2: Figure S1. Flowchart of the Malmo Offspring Study (MOS) population. Figure S2. Flowchart of the Malmo Prospective Study (MPP) population.


Moderate or severe dolichocephaly occurred in 21/26 infants (80.8%). Cranial index decreased over time . Brachycephaly and plagiocephaly were uncommon. No risk factors for severe dolichocephaly were identified. Our study shows that early detection of head shape and size anomalies utilizing 3D stereophotogrammetry is feasible and safe even in very preterm infants < 1500 g and/or < 32 weeks. 3D stereophotogrammetry could be used for timely identification of infants at risk for head shape anomalies. No specific risk factors for head shape anomalies were identified, especially not mode and duration of respiratory support.Head development is a surrogate for brain development in infants and is related to neurocognitive outcome. There is only limited knowledge on early extra-uterine head shape and size assessment in very preterm infants. Here, 26 very preterm infants with a mean gestational age of 29.1 ± 2.2 weeks and a mean birth weight of 1273.8 ± 427.7 g underwent serial stereophotogrammetric 3D head imaging in weekly intervals from birth to term-equivalent age. The main outcome was the longitudinal assessment of the ‘physiological’ preterm head development with cephalometric size  and shape parameters  according to chronological and postmenstrual age (PMA). Potential clinical risk factors for the development of an abnormal low cranial index  were analysed. In serial measurements of 26 infants, the estimated head volume  increased from 244 (226–263) cm Likewise, deformational head shape anomalies are known to be associated with suboptimal neurodevelopment6.In preterm infants, optimal early head (and weight) growth determines improved neurodevelopment7 and various risk factors predispose them for head shape anomalies. Given the fact that being born prematurely is non-physiological in itself, expecting a ‘physiological’ postnatal head development especially in very preterm infants is difficult. Particularly during the first weeks of life, preterm infants more often than term infants have bone mineral deficiency or softer skull. They are earlier exposed to gravitational forces, lateral positioning of the head and respiratory support partly with tight-fitting caps attached to respiratory devices. However, especially in low birthweight infants, head circumference (HC) tape-measurement is limited by suboptimal interobserver reliability8.Despite the clinical and scientific significance of head and brain size as well as head shape development, there are still substantial knowledge gaps regarding this topic. Especially preterm infants have a higher risk for insufficient head growth10 but routine implementation failed due to poor feasibility or cost-effectiveness. Providing a method that allows a bedside, fast and radiation-free image acquisition at an affordable price would enable to routinely identify shape anomalies as well as volumetric measurement of head growth. This could be a window of opportunity for potential preventive interventions, too. To address this, we recently described the feasibility and safety of 3D stereophotogrammetry for head assessment in neonatal patients during hospitalisation12.To assess head shape and volume, three-dimensional (3D) head assessment is favourable, particularly to characterize head shape anomalies in detail. Different radiation-free 3D techniques have been described for this purposeThis longitudinal study aims to analyse head shape and size physiology in very preterm infants from birth till term equivalent age using stereophotogrammetry.Between 21/02/2020 and 11/09/2020, consecutive patients were screened for eligibility, prospectively included and underwent serial non-invasive stereophotogrammetric 3D head imaging. Due to institutional regulations regarding the 2020 coronavirus pandemic, inclusion of new patients or image acquisitions were not allowed during the first lockdown in Germany between 16/03/2020 and 21/05/2020. Study inclusion criteria were prematurity with a birth weight < 1500 g and/or gestational age (GA) < 32 weeks. Study exclusion criteria were palliative/comfort care scenarios, inborn neurological disorders, synostotic head shape anomalies, lack of parental consent or expected out-of-hospital patient transfer before term equivalent age. If the first image could not be obtained at 33 weeks PMA at the latest, the patient was excluded from study participation. Exclusion criterion for a single time point image acquisition was any critical or clinically deteriorating health condition.For each patient, perinatal data was obtained from the medical records. Data of interest included sex, multiple birth status, GA, birth weight, body length and manually measured HC, birth presentation, mode of delivery and presence of asphyxia. At each time of image acquisition, postmenstrual age (PMA), body weight, manually measured HC and details on respiratory support were recorded. Respiratory support was sub classified according to duration of (a) invasive mechanical ventilation (IMV), (b) nasal continuous positive airway pressure (nCPAP) and (c) nasal high-flow therapy (nHFT). For all infants, neonatal morbidity was assessed including death, moderate or severe bronchopulmonary dysplasia (BPD), necrotising enterocolitis (NEC), intracerebral haemorrhage (ICH) ≥ III°, retinopathy of prematurity (ROP) ≥ III° and periventricular leucomalacia (PVL) as well as infection.Our clinical routine head sonography protocol included repetitive ultrasound assessments of all preterm infants on days 1, 3, 7, 14, and then biweekly until discharge or more frequently in case of abnormal findings at any time.For each patient, written informed parental consent was obtained prior to inclusion. In the case of the infant shown in Fig. 11. In brief, at each session we took ten images from various predefined angles. To reduce hair artifacts, facilitate 3D reconstruction and eye protection, all infants wore smooth nylon caps with textured applications and eye protectors , respectively. 217 image sets were acquired on the neonatal ward during routine patient care or while the infant was being held in their parents’ arms  was used. We previously described our neonatal 3D head imaging protocol in detailImages were edited—i.e. processed and converted to a common 3D data format (.stl) using the VECTRA Analysis Module (VAM) software version 6.2.3  and the MeshLab software version 2016.12 . Analyses were performed with the Cranioform software version 4.0 .13 and Ifflaender et al.14 are presented in Supplemental Table Predefined morphological planes and areas constitute the basis for 3D head measurements Fig. B. DefiniPatient data was handled using Microsoft Excel version 1906 . Numerical variables are expressed as mean ± standard deviation, categorical variables as percentages. Head parameters with 95% confidence intervals in dependence of age were estimated by polynomial linear regression with random effect patient. Weekly changes of head parameters with 95% confidence intervals were estimated by the same method adjusting for the values of the week before. Manual and digital measurements of HC were compared using Bland–Altman analysis. Associations between HC, cranial volume (CV) and body weight at time of image acquisition were assessed with Pearson correlation coefficient. Associations between dolichocephaly and numerical variables were assessed using the Mann–Whitney U Test. Associations between dolichocephaly and categorical variables were analysed with Fisher’s exact test. Test–retest reliability was assessed with the coefficient of variation. All statistical tests were two-sided with a significance level of 0.05. Statistical analyses were conducted using Stata/IC 16.1 for Unix .Of the 363 patients admitted to our neonatal unit during the study period, 45 met the inclusion criteria. Sixteen patients could not be included due to research restrictions during the first German lockdown in the 2020 coronavirus pandemic. The parents of three patients did not provide consent for study participation. All but four intended images (217 image sets) were acquired at the per protocol predefined time points. The remaining four image sets  could not be acquired due to coronavirus pandemic-related restrictions. There were no excluded patients.5/7 weeks PMA.Of the 26 very preterm infants included, 12 (46.2%) were female and 15 (57.7%) were multiples. Mean GA was 29.1 ± 2.2 weeks. At the time of the first image, the minimal weight was 805 g, and the youngest infant was 2715) and mean HC was 27.1 ± 3.0 cm. Additional results are reported in Supplemental Text Mean birth weight was 1273.8 ± 427.7 g  were intubated and mechanically ventilated. Overall, mean duration was 1.3 ± 2.9 days for IMV, 15.3 ± 12.7 days for nCPAP, and 18.2 ± 11.9 days for nHFT.In all patients, vitamin D, phosphorus and calcium levels were monitored and individually substituted to exclude bone mineral deficiency. Positioning regime did not differ within the study cohort and patients were equally put in prone and supine positions.16 or culture-proven sepsis was diagnosed in six infants (23.1%). No study patient developed (post-hemorrhagic) ventriculomegaly or hydrocephalus.NEC or PVL were not diagnosed in the here described cohort. Four out of 26 infants (15.4%) experienced in-hospital neonatal morbidity (as defined by above). One infant developed moderate BPD, one infant experienced ICH III° with intraparenchymal haemorrhage and two infants developed ROP ≥ III°. Clinical3 between 30 and 40 weeks PMA.Numerical digital cephalometric parameters (HC and CV) with 95% confidence intervals according to PMA are displayed in Fig. Manual and digital measurements of HC revealed little deviation. Specifically, the mean difference was − 0.01 (± 0.73) cm with limits of agreement (LOA) − 1.43 to 1.41 cm and a 95% confidence interval of − 0.11 to 0.09 cm . The CI decreased over time. By 38 weeks PMA at the end of the study period, it reached its nadir with 72.4% and a 95% confidence interval of 70.7–74.0. At discharge, 6/26 infants (23.1%) had normal CI, four (15.4%) had mild, nine (34.6%) moderate and seven (26.9%) severe dolichocephaly. Development of CI and presence of dolichocephaly in relation to chronological age and PMA are illustrated in Fig. Brachycephaly was present in 3/26 infants (13.0%) in the first 2 weeks of age, but never later. These three infants all developed dolichocephaly towards term equivalent age.Individual CI development for each single patient according to chronological age is presented in Supplemental Fig. Regarding plagiocephaly, at discharge, 20/26 infants (76.9%) had normal cranial vault asymmetry index (CVAI), three (11.5%) had mild, one (3.8%) had moderate and two (7.7%) had developed severe plagiocephaly. The development of CVAI and presence of plagiocephaly in relation to chronological age and PMA are illustrated in Fig. There were no factors identified to associate with severe dolichocephaly including sex, multiple birth, GA, birth weight, total duration of respiratory support, days of IMV, nCPAP or nHFT, neonatal morbidity, infection, or weight at discharge, respectively , but no dolichocephaly (CI min. 80.8%). The patient was not excluded from analysis because there was no evidence for post-hemorrhagic ventriculomegaly or hydrocephalus and to acknowledge ICH as a well-known complication of preterm infancy.first wave of the coronavirus pandemic in early 2020—a time in which clinical research has been severely disrupted worldwide22.Although still significant with regards to the special patient population, the number of study participants was relatively low. While the sample size was sufficient to demonstrate feasibility and safety of the new procedure, this may explain the surprising missing detection of potential underlying risk factors for dolichocephaly. As we used a novel technology, we pragmatically chose a single-centre study design and included consecutive patients to avoid selection bias. Unfortunately, we were not able to include as many patients as initially planned because the study conduction period fell in the time of the Following the predefined in- and exclusion criteria, all measurements were included into the analysis although one study patient developed high grade ICH which despite the absence of post-hemorrhagic hydrocephalus possibly influences the head shape and size development.Moreover, the here selected study design does not feature a control group. The reason was the nature of the studied phenomenon, in other words, there is no standard reference for extrauterine head development in very preterm infants.Finally, like with many novel technologies, data handling  is not yet fully automated for image sets acquired by hand-held cameras. This results in a somewhat cumbersome workflow rendering the method less likely to be clinically implemented at this point. A solution would be an automated image processing tool, analogue to the technology available for stationary 3D stereophotogrammetry systems.Using 3D stereophotogrammetry, evaluation of ‘physiological’ head shape and size development was feasible and safe even in very preterm infants < 1500 g and a PMA < 32 weeks. Being fast, accurate, radiation-free and inexpensive, 3D stereophotogrammetry seems suitable as a routine measure in neonatal care to assess head shape and size in infants at risk.Supplementary Information.


We aimed to determine the prevalence of late fetal mortality in Spain and risk factors for cesarean birth in women with stillbirth ≥ 28 weeks gestation between 2016–2019. (2) Methods: A retrospective observational study with national data between 2016–2019. A total of 3504 births with fetal dead were included. Sociodemographic, obstetrical and neonatal variables were analyzed using univariate and multivariate logistic regression (MLR), with cesarean birth with a stillborn ≥ 28 weeks gestation as the dependent variable. (3) Results: The late fetal mortality rate was 2.8 × 1000; 22.7% of births were by cesarean section. Factors associated with cesarean were having a multiple birth (aOR 6.78); stillbirth weight (aOR 2.41); birth taking place in towns with over 50,000 inhabitants (aOR 1.34); and mother’s age ≥ 35 (aOR 1.23). (4) Conclusions: The late fetal mortality rate increased during the period. The performance of cesarean sections was associated with the mother’s age, obstetric factors and place of birth. Our findings encourage reflection on how to best put into practice national clinical and socio-educational prevention strategies, as well as the approved protocols on how childbirth should be correctly conducted. The global world rate of fetal deaths from 22 weeks of gestation (wg) is estimated at 18.4 per 1000 births; this rate is equivalent to about 2.6 million fetal deaths each year [Late fetal death is defined as a “death occurring at or after 28 wg, before the complete expulsion or removal of the product of conception from the mother’s body, regardless of the duration of gestation” . PerinatA total of 97% of late fetal deaths occur in developing countries, which have a prevalence of 3% of all births. In developed countries, the prevalence is below 1% : for insThe etiology of fetal death is often unknown, despite being the subject of many studies ,10. In mRecommendations on the management and birth mode in the case of dead fetuses state that induced labor and the vaginal route should be given priority because they produce fewer complications, and because the woman can be discharged from hospital earlier . In factThe aim of this study was to determine the prevalence of late fetal mortality and risk factors for cesarean birth in women with a dead fetus of 28 or more weeks of gestation in Spain from 2016 to 2019 .This observational and analytical retrospective study employed the official information sources given by the Spanish National Institute of Statistics (INE)  on late A total of 3504 births were included, all with a gestational age of 28 weeks or more and which produced a stillborn at birth. Births under 28 wg were excluded. It is important to point out that it was the parents or relatives who registered the variables, which accounts for missing data in some of the variables; for example, the number of weeks of gestation. In fact, it is estimated that between 2010 and 2015 the underreporting rate in Spain for stillbirths of more than 28 wg was 7.6% ,19.The variables studied were: (i) maternal age (≥19/20–29/30–34/≥35 years); mother’s province of residence (Spanish province); educational level (primary or lower/secondary/university); country of origin (Spanish/rest of Europe/Africa/America/Asia-Oceania); mother’s marital status (married/single/separated-divorced); mother’s occupation (active/unemployed); place of birth ; size of town/city of residence ; number of fetuses (single/multiple); parity (primiparous/multiparous); gestational age (28–36/37–42/>42 wg); term birth (yes/no); type of birth ; intergenic interval (months); stillborn sex  and stillborn weight (grams).n) and percentages (%), while the numerical variables were expressed as mean and standard deviation (SD). Then, the risk of the independent variables for the cesarean birth variable and the crude odds ratio (OR) were calculated. Finally, a multiple logistic regression analysis (MLR) was performed with the independent variables which obtained the most significant values in the univariate analysis. Using the Wald statistic, we individually removed variables with a p value ≥ 0.15 from the model, and studied the possible interactions between the variables. Variables with a significance of over 0.05 were considered possible confounding factors. The goodness of fit of the model was calculated using the Hosmer-Lemeshow statistic, with a value of p < 0.05 considered significant. To carry out the statistical analysis, we used the following program: IBM SPSS Statistics version 25.For the data analysis, we caried out a descriptive analysis of the variables, with the categorical and ordinal variables expressed as numbers  ,19, if aWe analyzed a total of 3504 births resulting in fetal death, of which 9.8% were multiple births. A total of 2740 (94.3%) of fetal death occurred prior to delivery, 166 occurred during delivery (5.7%) and 598 were missing data. As can be seen in The mean number of weeks of gestation after which the birth occurred was 34.7 (3.8) weeks, with a minimum of 28 and a maximum of 42. Furthermore, 37.2% were term births and 62.8% were preterm; 77.3% were vaginal births, while the remaining 22.7% required a cesarean section, including women with a medical history of previous cesarean sections. An total of 52.8% were primiparous, 40% were married mothers and 60% were single, separated or divorced. Only 20% had studied at university level. With regards to country of origin, 75.8% were Spanish, 5.4% from the rest of Europe, 11.9% from Africa, 4.7% from America and 2.2% from Asia and Oceania. The global rate of cesarean births in towns/cities with over 50,000 inhabitants was 23.4%, while the figure for towns/cities with under 50,000 inhabitants was 18.3%. p < 0.001). Among multiparous women, statistically significant differences were found when comparing this data between births in towns/cities of 50,000 inhabitants or more (24% cesarean sections) with smaller towns/cities ; women of Spanish nationality had a higher rate of cesarean sections than foreign women ; this also occurred in women with fetuses of 4000 g or over compared to lower weights . In both groups, the cesarean section rate was higher than that recorded in women with multiple births.p < 0.001); stillborn weight ; births that took place in towns/cities with over 50,000 inhabitants ; and mother’s age of 35 or over .According to the latest report from the European Perinatal Health Report (EUROPERISTAT), published in 2015, when compared with the data from the previous 2010 report, the rate of late fetal deaths has decreased in some European countries, such as Cyprus, Belgium, Denmark, Ireland, Greece, Malta, Holland, Poland, Romania, Lithuania, Austria, England and Norway. However, there are also many countries where these deaths have increased, as in Germany, Estonia, Spain, France, Luxembourg, Hungary, Portugal, Slovenia, Slovakia, Finland, Sweden, Iceland and Switzerland . This daIn the present study, although analysis does not focus on the causes of late fetal mortality, prematurity occupies 2/3 of the sample, with great prematurity (<32 weeks) accounting for 31.7%. Note that prematurity is known to be associated with the risk of late fetal death , and it The mode of birth after fetal death depends on the gestational age, the mother’s obstetric history and even her preferences, so it is up to health professionals to assess the risks and benefits in each case in order to achieve the most favorable results. The most common option consists of inducing labor with misoprostol to attempt vaginal birth and thus avoid cesarean section ; howeverOur findings show that the factors associated with cesarean birth were the mother’s advanced age, multiple births, fetus weight and the size of the town/city where the birth took place. Ramseyer et al. also found that older women had a higher risk of cesarean section . Other aRegarding the fetus weight, coinciding with our results, Rossi et al. found that the risk of cesarean section increased in large for gestational age fetuses . One notThe main limitation of this study lies in the rate of under-reporting of data to the National Institute of Statistics (INE) by parents or relatives, which accounts for the missing data in some variables. In fact, the data declared by the INE on late fetal deaths do not appear to tally with those shown in this study, although it must be remembered that our results have been obtained from birth records, while the data issued by the INE include the total number of dead fetuses (including those from multiple births). We believe that the INE has taken into account other variables in addition to gestational age to determine the status of late fetal death, or that there must be considerable variation in the limit of 28 wg included in the family’s declaration of this data. However, regardless of the under-reporting of the data, the number of records included 3504 births, and the fact that the total number of late fetal deaths during a 4-year interval were used allows us to generalize the results, which is the main strength of our study. Other limitations were the missing data on causes of cesarean sections and those derived from retrospective studies. In addition, we have a crude cesarean section rate, which is not very objective data by which to identify whether cesarean sections were indicated following clinical recommendations in the guidelines or for unjustified reasons.In summary, late fetal mortality in Spain still shows an upward trend. In addition, the route of birth chosen in late fetal death can affect future births. The percentage of cesarean sections was high and could be associated with multiple or twin births, larger fetuses, the birth taking place in towns/cities with over 50,000 inhabitants and mothers over 35 years of age. Our findings emphasize the need to promote research into the causes of late fetal mortality, as well as to implement clinical prevention strategies in the birth process. Health professionals should put into practice the official national protocols on managing births with a dead fetus in order to reduce the number of cesarean sections, limiting their use to specific cases.


The COVID-19 pandemic had a severe impact on women’s birth experiences. To date, there are no studies that use both quantitative and qualitative data to compare women’s birth experiences before and during the pandemic, across more than one country.To examine women’s birth experiences during the COVID-19 pandemic and to compare the experiences of women who gave birth in the United Kingdom (UK) or the Netherlands (NL) either before or during the pandemic.This study is based on analyses of quantitative and qualitative data from the online Babies Born Better survey. Responses recorded by women giving birth in the UK and the NL between June and December 2020 have been used, encompassing women who gave birth between 2017 and 2020. Quantitative data were analysed descriptively, and chi-squared tests were performed to compare women who gave birth pre- versus during pandemic and separately by country. Qualitative data was analysed by inductive thematic analysis.Respondents in both the UK and the NL who gave birth during the pandemic were as likely, or, if they had a self-reported above average standard of life, more likely to rate their labour and birth experience positively when compared to women who gave birth pre-pandemic. This was despite the fact that those labouring in the pandemic reported a lack of support and limits placed on freedom of choice. Two potential explanatory themes were identified in the qualitative data: respondents had lower expectations of care during the pandemic, and they appreciated the efforts of staff to give individualised care, despite the rules.Our study implies that many women labouring during the COVID-19 pandemic experienced restrictions, but their experience was mitigated by staff actions. However, personalised care should not be maintained by the good will of care providers, but should be a priority in maternity care policy to benefit all service users equitably. Pregnancy is a unique and life-changing event that is associated with new experiences and strong emotions for many women and birthing people (further ‘women’) ,2. EventBetween 2020 and 2022 several studies have evaluated the birth experiences of women during the COVID-19 pandemic. For instance, an Italian qualitative study concluded that pregnant women during the pandemic experienced fear, sadness, and uncertainty when they visualised their upcoming birth . Two UK To address this gap and provide an in-depth understanding of women’s birth experiences during the COVID-19 pandemic, we used qualitative and quantitative data to compare the experiences of women and childbearing people who gave birth in the UK or the NL either before or during the pandemic. The UK and the NL are European countries with comparable maternity care systems, and, by population size, experienced similar numbers of COVID-19 infections. Their approach to the pandemic in maternity care was somewhat different, with the NL having a more community-based approach and the UK offering more hospital-centric care, but having greater structures in place for service user organisations input . A compaThis study was undertaken as part of the UKRI-ESRC funded Achieving Safe and Personalised maternity care In Response to Epidemics (ASPIRE COVID-19) study, which included an analysis of responses to the international Babies Born Better survey (B3-survey) version 3. The survey includes both quantitative questions about labour and birth experiences, and qualitative questions designed to understand what underlies both positive and negative responses. To our knowledge this is the first mixed-method study about childbirth experiences pre- and during the COVID-19 pandemic. Our research question was: What were the labour, birth, post-partum and neonatal care experiences of UK and NL women before and during the COVID-19 pandemic and what explains any differences?This study is based on analysis of the quantitative and qualitative data from the online B3-survey version 3. The B3-survey was designed with help of the EU-funded COST IS1405 network to assess and interpret differences in the quality of maternity care within and between countries. The survey is designed to capture women’s views about what went well in their maternity care experience and what could have worked better. Our study focuses on the lived experience of our participants. Therefore, we explicitly did not look at whether the events the participants described as their experience have actually happened in the way they remember them.The B3 survey has been run since February 2014, with an overall response to date of over 97,000 women in 25 languages from 86 countries –22. The no problems, minor and severe medical and non-medical problems. Self-reported standard of life was assessed with the following question: ‘compared to most people in this country, I think my standard of life is…’ followed by a Likert scale comprising the terms much worse, below average, average, above average and much better. Women are asked to rate their overall birth experience with the following question: ‘How do you feel about your labour and birth experience?’ using a Likert scale of mostly a very good experience, mostly a good experience, some of it was good and some of it was bad, mostly a bad experience or mostly a very bad experience.The survey captures demographics , clinical factors (such as type of birth and problems during pregnancy). The place name or postcode of the birth location was also captured. Problems during pregnancy were self-reported by the participants and were categorised as After that, respondents were asked to record the three most positive aspects of the care they received, and three aspects that could have improved their birth experience. They were then invited to imagine that a close relative or friend who was pregnant had asked for an honest description of the care they had received, and to record what their response would be. The survey ends with an open question where the woman can add any additional information about their labour and birth that they think might be relevant.Participants were divided into 2 categories: ‘pre-COVID-19’ and ‘COVID-19’. A participant belonged to the ‘pre-COVID-19’ category if they gave birth before 1 March 2020 and to the ‘COVID-19’ category if they had a baby from 1 March 2020 onwards. Participants who did not record a date of birth of their baby or gave birth pre-2017 (n = 47) were not included in the analysis related to COVID-19.Descriptive analyses were performed on all quantitative data in the survey, firstly by whether the participant gave birth in the UK or the NL, and then by categorising participants into ‘pre-COVID-19’ and ‘COVID-19’. Chi-squared tests were performed on categorical variables by COVID status, separately by country and between countries. Fisher’s exact test was used when assumptions for chi-square analysis were not met.The dependent variable ‘birth experiences’ was then dichotomised into two categories: positive and not positive. Positive contained responses ‘mostly good’ and ‘quite good’ and not positive contained responses ‘some good, some bad’, ‘quite bad’, ‘mostly bad’. The dichotomisation of birth experience was grouped in this way based on consensus between the authors. The not-positive category existed of answers from women that included the word ‘bad’ to describe their experience. We included the category ‘some good, some bad’ in the not positive category, since we believe that the decision of women to include the word ‘bad’ in their answer indicated that there were several things they disliked about their childbirth experience. Standard of life was also dichotomised into ‘below average & average’ and ‘above average’. Birth experiences and standard of life were separately compared in the pre-COVID-19 and COVID-19 time periods and also separately by country, because it is known that a higher than average standard of life might have impacted childbirth experiences during the COVID-19 pandemic . Stata vWe analysed responses to the two open-ended questions in the B3 survey: question 1) “In the place where you gave birth, what were the three most positive experiences of your care?” and question 2) “What do you think could have made your experience better?”. We analysed the answers using Braun and Clarke’s  inductivFirst, we used MAX QDA version 2020.4.1 to generate the initial codes from the data, and to aid us in recognising patterns in the data as a basis for thematic interpretation. We decided to use a software package due to the large number of respondents in the survey. MAXQDA was chosen as it is an intuitive data management system that offers the advantages of efficient data handling, while being very straightforward to use. The initial codes were used to recognise patterns and were sorted into groups until thematic saturation was reached. There was no new data included after thematic saturation was reached. For each coding group, we then looked at the answers given by women who had given birth before or during the COVID-19 pandemic. The initial themes were developed by LB, and were reviewed and refined through discussions with all authors until consensus was reached. The writing process was guided by the Consolidated Criteria for Reporting Qualitative Research (COREQ) . Since mOur research team comprised seven women with different backgrounds, including midwifery, psychology, statistics, and women’s studies. At the beginning of the analysis phase, we all believed that restricting women’s rights during childbirth in an attempt to prevent COVID-19 could lead to short and long-term effects on women’s psychological wellbeing. While prevention of infection is important, lack of attention to psychological wellbeing may generate greater harm than benefit in the longer term ,27. We pThe confirmability of our study is evidenced by the credibility of our analysis which was strengthened through our reflexive accounting, by discussion of codes and themes across the author group, and by using participants words to illustrate our themes. Furthermore, through transferability, via a careful description of the context of our survey and the demographics of the respondents; and dependability through the detailed description of the steps we took in undertaking the study.In the Netherlands the study was submitted to the Medical Ethics Review Committee of the VU University Medical Centre (reference number 2020.255). No ethical approval was needed, since the Medical Research Involving Human Subjects Act did not apply to this study, as there was considered to be no infringement on the physical and/or psychological integrity of the participants.In the United Kingdom the study was approved by the University of Central Lancashire (UCLan) Committee for Ethics and Integrity (STEMH 449 Amendment_1Jun20).All the participants were above eighteen years old and gave written informed consent before they started the survey. The survey is completely anonymous, so they were aware that they could not withdraw their data once they had submitted their responses.A total of 2203 completed surveys from the UK and The NL were recorded between June and December 2020. 1303 (60%) of responses were from the UK and 900 (40%) were from the NL. Overall, 31% (n = 678) of respondents gave birth during the COVID-19 pandemic (March-December 2020); 36% (468) of all UK respondents, and 23% (n = 210) of all respondents from the NL .X2 (1) = 4.2, p = .041) but no difference was found in the NL  reported pregnancy problems pre-COVID-19 and 40% (n = 193) during COVID-19. There was a weak statistically significant difference in the UK (n the NL .X2 (4) = 15.38, p = .004) in birth setting in the UK with more women giving birth in hospital during COVID-19 pandemic compared to pre-COVID-19. No such difference was found in the NL, but the NL had a higher rate of homebirth overall among the respondents: 44% (n = 399) compared to the UK; 18% (n = 230).In the NL women reported a higher percentage of having a vaginal birth without help in both time periods compared to the UK. No statistically significant difference was found in either country between COVID-19 time points for type of birth . There wMost of the described demographics are in line with the population numbers, but the home birth rate in our sample is higher than in the overall population, for both the UK and the NL ,29.The NL had a higher percentage of women reporting a very good birth experience 65% (n = 581) compared to the UK 48% (n = 624), which is a statistically significant difference between the two countries . No significant differences were found in either country for labour and birth experiences pre and during the COVID-19 pandemic for the respondents as a whole . At bothIn the UK, similar rates of women reporting average and below standard of life had positive labour and birth experiences pre-COVID-19 64% (n = 233) compared to during the COVID-19 pandemic . Women reporting a higher standard of life were non-significantly more likely to report better experiences if they gave birth during the pandemic than those who gave birth before COVID-19 (71% vs 65%).In the NL, similar patterns were seen, with the more positive birth experience for women who gave birth during the pandemic reaching statistical significance for women self-reported higher standard of life (94% vs 84%) .Given that the findings that the experiences of women were similar or better during Covid-19 than pre-Covid-19 are in direct contrast to many other studies in this area, we examined the responses to two open questions to try to identify reasons for our unexpected results. Our thematic analysis identified two themes underpinning negative experiences: 1) Lack of support; 2) Limits placed on freedom of choice. Two further themes might explain why some reported experiences were more positive than anticipated: 3) Lower expectations of care during the pandemic; and 4) Efforts of staff to give personalised care, despite the rules. All four themes were more present in the accounts of women who gave birth during the pandemic.Responses to the question ‘What do you think could have made your experience better?’ indicate that women who gave birth during the COVID-19 pandemic revealed a lack of support before, during and after childbirth. For some women this was associated with fewer staff being available, or by shorter or more distant contacts with staff due to COVID-19 social distancing measures:When I unexpectedly laboured I did not receive enough care waiting for my COVID test and labouring waiting for C section.’ ‘More presence of the midwife and nurse during childbirth’ ‘Besides the lack of professional support, women experienced a lack of informal support as well. This was because COVID-19 measures made it more difficult for women to receive their chosen labour and post-partum support from a partner, family member and/or doula, due to restrictions in both countries.Because of the corona measures my partner was not allowed to be there during overnight stay before the birth’ ‘Partner being able to stay longer on the ward—limited visiting due to covid’ ‘Other family being able to visit the post-natal ward’ ‘The majority of the participants considered freedom to make choices about their labour and birth to be very important. While many women reported that their freedom to make choices was respected during childbirth, even during the COVID-19 pandemic, some of those giving birth during restrictions noted limitations to this freedom. This was particularly noted in terms of choices about place of labour and birth in the UK, due to some home birth services being closed.Home birth service’ ‘In contrast, none of the respondents from the NL noted restrictions in home birth services, and for some, freedom to give birth at home during the pandemic was a positive factor in their experience:That I could give birth at home’ ‘Furthermore, some respondents experienced limitations in other parts of their birth experience, such as the possibility to choose birth positions or a water birth:Due to Covid I was not allowed a water birth.’ ‘As the previous results have shown, many of the women who gave birth during the COVID-19 pandemic in both the UK and the NL were alone when they wanted companionship , and had less freedom of choice. This being the case, it is surprising that the quantitative data suggest that they were equally, or even more likely to report that their birth was a positive experience compared to women who gave birth before the pandemic. One of the reasons behind this might be that, during the pandemic, women had lower expectations for their labour and birth experience, due to national and local restrictions. For example, the following examples were cited as distinct positives of care by two women giving birth during the pandemic, even though this would be seen as basic care standard in pre-pandemic times:My own [primary care] midwife could attend the birth’ ‘Flexibility so I could be supported by my husband in a stressful situation’ ‘Many women in both groups, pre-COVID-19 and COVID-19, valued the importance of known, competent, caring and empathic care providers. The women who gave birth during the COVID-19 pandemic tended to be complimentary about their care providers, particularly in relation to their efforts at a difficult time.The doctors and nurses were very helpful and flexible (despite Corona measures)’ ‘Several women were grateful for maternity care providers making exceptions to the COVID-19 measures.This was particular to the time of our birth, when there were still many Covid-19 related restrictions in place, but the healthcare providers allowed my partner to be there from the beginning of my induction drip rather than waiting until 4cm dilated which I know was the case in other Trusts/hospitals’ ‘One participant acknowledged that her childbirth experience during the pandemic was challenging, but complimented her midwives that they made the experience slightly better.My midwives were very supportive and helpful. They [my midwives] made giving birth during a pandemic slightly better’ ‘In this mixed-method study we compared the childbirth experiences of UK and NL women responding to the international B3 survey who gave birth before and during the COVID-19 pandemic. In general, women giving birth in the NL were much more likely to rate their care as positive than women giving birth in the UK, at both time points, and across all self-report standard of life categories. In each country, women who gave birth during the COVID-19 pandemic were, on average, at least as positive about their childbirth experiences as women who gave birth before the COVID-19 pandemic. Moreover, the NL women who self-reported an above average standard of life were even more positive about their birth experiences if they gave birth during the COVID-19 pandemic, and while this trend was also seen in the UK data, it did not reach statistical significance. This is despite the fact that many women labouring during the pandemic reported having less support, choice and control than those in the pre-pandemic period. Based on the qualitative analyses, two mitigating factors appeared to contribute to this unexpected finding: women seemed to have lower expectations during the pandemic, and they appeared to appreciate that care providers tried hard to personalise care, sometimes despite the rules they were supposed to be following.This study contributes to the ongoing evidence that the COVID-19 pandemic has had an impact on women’s labour, birth, post-partum and neonatal care experiences, and the mental health of women, partners, and their babies –32. WomeDespite the restrictions to companionship and freedom to choose, our quantitative data indicate that survey respondents who laboured and gave birth during the pandemic phase were, on average, at least as positive about their labour and birth experiences as those giving birth before this point. This is in direct contrast to most surveys to date ,40. The The strengths of our study include the large number of responses to the B3 survey both before and after the pandemic, the ability to compare birth experiences between two European countries with similar social structures, and the use of both quantitative and qualitative data. The combination of methods gave us the opportunity to explain some of the unexpected findings in the quantitative data. As far as we are aware there are no other published studies to date that can make this comparison for women using childbirth services before and after the pandemic. Furthermore, our team consisted of people from a range of different disciplines, which contributed to investigator triangulation and therefore the trustworthiness of the results.However, our study has some limitations. Since the data were downloaded from the survey platform in December 2020, more women who gave birth during COVID-19 responded soon after their birth than women who gave birth pre-pandemic. This might have led to different levels of recall bias between the two groups. Although memory for the actual events of labour and birth is generally stable over time, there is some evidence that affective memories may become less positive, particularly if the labour or birth were difficult . FurtherWomen having home births were overrepresented in both countries. However, this does not explain the higher percentage of positive responses in the NL, since women having home births tend to be more positive in their responses, so the over-representation of home births in the UK suggests that, with a representative sample from both countries, these differences would have been even greater.In this study, respondents in both the UK and the NL who gave birth during the pandemic were, on average, as likely, or more likely to rate their labour and birth experience positively when compared to women who gave birth pre-pandemic. This was despite the fact respondents who gave birth during the pandemic reported lack of support and choice. This apparent paradox may be partly because women had fewer expectations of the care they were going to receive, which made them value normal care practices more. There is also evidence that they valued the work of maternity care providers who persisted with giving individualised care during the COVID-19 pandemic, despite the constraints of resources and rules, and that this influenced positive care ratings. Our study implies that women were adversely affected by COVID-19 restrictions during their labour and birth, but that there were mitigating factors for some women, especially those with an above average self-reported standard of life. Equitable personalisation of care is important during a crisis as well as in normal times, and should be part of general policy in maternity care and routine implementation in actual practice to benefit all service users, rather than being maintained for some, and, even then only through the willingness of staff to go ‘above and beyond’.


Darwin’s theory of sexual selection provides a useful framework for understanding the behavior of stepparents. A non-human animal whose new mate has dependent young may kill, ignore, or adopt the predecessor’s progeny. The third option has been interpreted as courtship (“mating effort”), and whether selection favors such investment over killing or ignoring the young apparently depends on aspects of the species-typical ecology and demography. The tripartite categorization of responses is a simplification, however, There is variability both within and between species along a continuum from rejection to “full adoption.” The average stepparent invests less than the average birth parent, but more than nothing. Human stepparents have often been found to kill young children at higher rates than birth parents, but stepparental infanticide cannot plausibly be interpreted as a human adaptation, both because it is extremely rare and because it is almost certainly more likely to reduce the killer’s fitness than to raise it. How sexual selection theory remains relevant to human stepparenting is by suggesting testable hypotheses about predictors of the variability in stepparental investment. A hundred years later, Darwin’s second great theory had still inspired little further theorizing apart from Sexual Selection and the Descent of Man, 1871–1971, an edited volume celebrating the centenary of Darwin’s opus . Although she clearly favored this hypothesis, and bolstered it with an abundance of observational and circumstantial evidence, she also identified areas where further evidence would be needed to conclusively dispose of the alternative possibility that infanticide was just a non-adaptive byproduct of something else.American Scientist, a semi-popular magazine whose subscribers, in a pre-internet age, included many behavioral biologists. Here, she was no longer so cautious: Her title, in a large bold font, was “Infanticide as a Primate Reproductive Strategy” and a subheading, also in an over-sized font, read “Conflict is basic to all creatures that reproduce sexually, because the genotypes, and hence self-interests, of consorts are necessarily non-identical. Infanticide among langurs illustrates an extreme form of this conflict.” She clearly explained the theory while providing engaging accounts of her observations, of relevant langur natural history, and of prior observations, extending back more than a century, which had partially anticipated and now reinforced her insights. Early reaction to Hrdy’s argument was muted and mixed, but she inspired some researchers e.g., , and sheSome authors e.g.,  opposed Hrdy’s sexually selected infanticide hypothesis has been widely vindicated, and no serious controversy remains about its applicability to various species in the natural world . Such beThe best documented cases of sexually selected infanticide initially came from studies of mammals, and the perpetrators were always males. Female mammals also kill young who are not their own, but never in order to usurp the parental efforts of the fathers . Indeed,In other vertebrate classes, the situation facing the two sexes is often crucially different. Females usually oviposit shortly after their eggs are fertilized (birds), or even before (many fishes and amphibians), with the effect that major male roles in even the earliest forms of parental care can more readily evolve. One consequence has been the recurrent evolution of what is, from our mammal-centric perspective, “sex role reversal” . In sevepost hoc by the theory of sexual selection, which is thus predictively empty? Not if the theory directs us to hypotheses about likely correlates and predictors of these alternative responses.This sort of sex role reversal is rather rare even among birds, however . More thAlthough de facto unions). There is no reason to doubt that these things have been true for hundreds of generations.The “mating effort” interpretation of stepparental tolerance and care seems clearly to be applicable to our own species . The steThe “family studies” literature is potentially misleading in these regards. Focusing solely on trends in the rich world over a few decades, many social scientists have endorsed There is abundant evidence that the feelings and behavior of human stepparents differ from those of birth parents in ways that are consistent with the view that stepparents are more restrained in their willingness to invest (reviews by The various Cinderella effects described in the preceding paragraphs were documented in samples of parents that were drawn in such a way as to be representative of their respective populations, and presumably portray average levels of discrimination by parents in general. A less frequent but extremely serious domain of stepchild disadvantage is that of child maltreatment, and it is in the most extreme forms that the largest Cinderella effects have been found. In “baby battering” cases in which shaking and/or blows to the head or abdomen by enraged caretakers were fatal, the case numbers are often indicative of a greater risk at the hands of stepfathers than birth fathers on the order of 100-fold or more. In the first published report exemplifying this contrast, de facto marriage (The evidence regarding lethal abuse by stepmothers is much sparser than is the case for stepfathers. Although stepmother cases exist in all large homicide data sets, small children so rarely reside with them that any estimate of a homicide rate must have huge confidence intervals. However, on the basis of analyses of national data from the FBI, marriage .Stepmother-stepfather comparisons can be made with more confidence when we turn to non-lethal child abuse. Oddly, although massive Cinderella effects in child homicide have been well documented in several countries, there have been relentless efforts to promote skepticism about their reality. Detailed rebuttals of some prominent examples are provided by Can infant-killing by replacement mates be understood as a sexually selected adaptation in human beings, as it is in Hanuman langurs, lions, and many other species? Clearly not! Infanticide by human stepparents fulfills none of the criteria for identifying adaptation, as laid out by We moved to New Zealand in May, 2019, and with long-standing interests in family violence and substitute parenthood, we were curious to see where our new home stood with respect to these problems. Soon after our arrival, a relevant murder trial was in the news . On JuneFilicides by birth fathers differ from those perpetrated by stepfathers in ways that indicate distinct motives. These contrasts between filicides perpetrated by stepfathers and those by birth fathers are readily interpreted as indicative of motivational differences whereby stepfathers more often resent the children and their obligations to them. Killings by birth fathers are sometimes brutal, too, but they are proportionately more likely to involve smothering, gassing, and other less assaultive methods. And even when the cases are brutal, filicidal birth fathers rarely if ever offer explanations for their acts like that of another New Zealander who recently killed his 17-month-old stepson when asked to look after him while the mother went out with a girlfriend: In the agreed statement of facts presented at his trial, the killer explained that he was “tired of being treated as the babysitter” . ParentaThere is a large professional literature, and an even larger self-help literature, dealing with reducing tensions in stepfamilies. One point on which there appears to be near unanimity is that it is a mistake to pretend that a stepfamily is a birth family, or to expect that it will, with time, become psychologically indistinguishable from one e.g., . The WakIt warrants emphasis that stepparent-stepchild relationships need not be toxic, and usually are not. Many children benefit from the presence and involvement of a stepparent  and onlymore hostile toward the resultant stepchildren than other stepfathers, despite having resided with them from birth.It is often suggested that if a stepfather had been able to bond with his stepchild from birth, he would feel and act like a birth father. The Wakefield case provides reason to doubt this, and so does the only systematic test of which we are aware: In an observational study of men’s interactions with children in a Trinidadian village, That said, there is evidence that ratings of stepparent-stepchild relationship quality, net of the stepchild’s current age, increase as a function of the relationship’s duration e.g., . To whatHomo sapiens? We have argued that killing stepchildren has clearly not been selected for in the human animal, but must instead be understood as the maladaptive tail of the “rejection” end of an invest-reject distribution, and that non-lethal abuse of a sort that damages the child and thereby raises investment costs is surely maladaptive, too. However, there is a range of lesser forms of maltreatment that may or may not serve the pertrator’s interests, and one might, in principle, propose hypotheses about specific, fine-grained, forms of investment and divestment. We suggest, however, that the adaptations underlying partial investment are probably best characterized at the abstract level of discriminative parental solicitude, and the most promising adaptationist hypotheses for future research are likely to be ones that concern facultative responsiveness to the same ecological and demographic variables that are relevant to the cross-species variability in stepparental response that Rohwer first described and discussed. Candidate variables include cues of local sex ratios and of the local levels of marital stability, mortality, requisite resources (e.g., es e.g., . and envMD wrote the manuscript and GP edited it. Both authors conceived the manuscript together, contributed to the article, and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.