This systematic review summarizes the association of climate change, including heat, ozone, and fine particulate matter, with adverse pregnancy outcomes, such as preterm birth, low birth weight, and stillbirth, in the US. Are increases in air pollutant or heat exposure related to climate change associated with adverse pregnancy outcomes, such as preterm birth, low birth weight, and stillbirth, in the US?In this systematic review of 57 of 68 studies including a total of 32 798 152 births, there was a statistically significant association between heat, ozone, or fine particulate matter and adverse pregnancy outcomes. Heterogeneous studies from across the US revealed positive findings in each analysis of exposure and outcome.The findings suggest that exacerbation of air pollution and heat exposure related to climate change may be significantly associated with risk to pregnancy outcomes in the US. Knowledge of whether serious adverse pregnancy outcomes are associated with increasingly widespread effects of climate change in the US would be crucial for the obstetrical medical community and for women and families across the country.2.5), ozone, and heat, and the association of these factors with preterm birth, low birth weight, and stillbirth.To investigate prenatal exposure to fine particulate matter  reporting guideline.2.5 or ozone was associated with increased risk of preterm birth in 19 of 24 studies (79%) and low birth weight in 25 of 29 studies (86%). The subpopulations at highest risk were persons with asthma and minority groups, especially black mothers. Accurate comparisons of risk were limited by differences in study design, exposure measurement, population demographics, and seasonality.Of the 1851 articles identified, 68 met the inclusion criteria. Overall, 32 798 152 births were analyzed, with a mean (SD) of 565 485 (783 278) births per study. A total of 57 studies  showed a significant association of air pollutant and heat exposure with birth outcomes. Positive associations were found across all US geographic regions. Exposure to PMThis review suggests that increasingly common environmental exposures exacerbated by climate change are significantly associated with serious adverse pregnancy outcomes across the US. Two components of air pollution that are exacerbated by climate change and continued use of fossil fuels are fine particulate matter less than 2.5 μm in diameter (PM2.5) and ozone.13These adverse health effects are most consequential to at-risk populations, which include a high number of pregnant women and developing fetuses.2.5, ozone, and heat and preterm birth, low birth weight, and stillbirth. Although these associations have largely been studied in a global setting,17 we focused specifically on the US population, in which these exposures are increasingly common.In this review, we assessed the associations between exposure to PM19 This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline.For this systematic review, we evaluated evidence of the association between air pollution and heat on the adverse obstetrical outcomes of preterm birth, low birth weight, and stillbirth. The Arskey O’Malley methodologic framework for a scoping review was used.2.5 or ozone associated with increased risk of preterm birth? Is prenatal exposure to PM2.5 or ozone associated with increased risk of low birth weight? Is prenatal exposure to PM2.5 or ozone associated with increased risk of stillbirth? Is prenatal exposure to heat associated with increased risk of preterm birth? Is prenatal exposure to heat associated with increased risk of low birth weight? Is prenatal exposure to heat associated with increased risk of stillbirth?The following specific key questions were addressed in this review. Is prenatal exposure to PM2.5 or ozone with or without other criteria pollutants or heat and the adverse obstetrical outcomes of interest were included.Studies published from January 1, 2007, to April 30, 2019, on US populations were deemed eligible. Studies that included either PMDetailed study inclusion and exclusion criteria for the systematic review are given in the Comprehensive literature searches were performed using the ClinicalTrials.gov website, PubMed, MEDLINE, Cochrane Library, and Cochrane Collaboration Registry of Controlled Trials. Medical Subject Headings (MeSH) terms are given in the With use of the Arskey O’Malley methodologic framework, study selection was focused post hoc to the exposures and outcomes specified. Race/ethnicity was identified in accordance with the studies reviewed and was analyzed to determine whether one race/ethnicity appeared to have a stronger association than others present in these categories. Results were organized into summary of evidence tables and presented qualitatively to describe the degree of heterogeneity in study designs, types of exposures, outcome measurements, and settings. Because of heterogeneity of environmental exposures among the studies and the variable manner of data reporting, quantitative estimates of pooled effects were not generated.2.5 from vehicle traffic and wildfires). The review presented the primary findings in summary of evidence tables for each key question and tabulated the preponderance of evidence that found significant associations . The overall number of births were included in the review, and the A pooled analysis or meta-analysis was not performed because of the heterogeneity of the study populations across geographic locations and the heterogeneity of exposures  on air pollutants and 10 (15%) on heat . There w2.5 and ozone, there were 24 (41%) studies on preterm birth, 29 (50%) on low birth weight, and 5 (9%) on stillbirth. Of the 58 studies addressing air pollution, 56 (96%) included PM2.5, 23 (40%) included ozone, and 21 (36%) analyzed both. Of these, 48 studies (84%) found a significant association between exposure to air pollutants and adverse birth outcomes  on preterm birth, 3 (30%) on low birth weight, and 2 (20%) on stillbirth. Nine of the 10 articles (90%) found a significant association between exposure to heat during pregnancy and adverse birth outcomes .2.5 and/or ozone with preterm birth  also analyzed ozone.There were 24 included studies evaluating the association of maternal exposure to PM2.5 whole-pregnancy exposure, the risk increased by a median of 11.5% . Six of these reports (54%) measured associations with preterm birth using a whole-pregnancy median of 3.9 μg/m3  of PM2.5 exposure. For example, in a study of traffic-generated PM2.5 in Los Angeles and Orange County, California, Wu et al20 found that preterm birth overall increased 3% , deliveries less than 35 weeks increased 7% , and deliveries less than 30 weeks increased 18%  per IQR of 1.35 μg/m3.Of the 11 studies analyzing PM22; each measured the association by IQR, from 7.1 to 11.53 parts per billion (ppb). Ha et al21 found an overall 3% increased risk of delivery before 37 weeks and 13% increased risk for deliveries before 32 weeks per IQR of 7.1 ppb. In a report on 34 705 singleton births and first-trimester ozone exposure in Pennsylvania, Lee et al23 found a 23% increase in risk per IQR of 16.8 ppb.Of the 4 studies analyzing ozone whole-pregnancy exposure, 2 (50%) found an increased risk from 3% to 9.6%24 Other subgroups identified in 2 studies each included younger and older mothers, those with less educational level, and those with government insurance or lacking early prenatal care.Ten studies reported the association of racial/ethnic disparities with increased risk of preterm birth among mothers in minority groups; 8 of the studies noted higher risk for black mothers, which was the most consistent finding among the subgroups. One study analyzing subgroups revealed a higher risk for preterm birth among patients with asthma.2.5 and preterm birth, measuring exposures during the whole pregnancy, by trimester, or by month of birth.29 Salihu et al29 found no significant association with preterm birth and above the median 11.28 μg/m3 PM2.5 exposure overall in a retrospective cohort in Florida but showed an 8% increased risk of preterm birth in association with 3-way interaction of PM2.5, fine particulate matter less than 10.0 μm in diameter, and coarse particulates. Another study28 used a nationally representative sample of higher-risk births and found no association of ozone exposure and a 3% odds per parts per million reduction in preterm birth rates with PM2.5.Five studies showed no association between PM2.5 and/or ozone with low birth weight  of whole-pregnancy exposure showing increased risk of low birth weight analyzed the association of IQR increases in PM2.5, which ranged from 2.0 to 6.9 μg/m3. In Massachusetts and Connecticut, Hyder et al10 found an 8% increased risk per IQR increases of 2.41.Eight studies examining whole-pregnancy exposure to PM33 found that whole-pregnancy exposure to ozone was associated with a significant increase in risk of low birth weight; 2 of them33 noted a 6% to 13% increased risk per IQR (7.4-11.5 ppb). Among 74 416 live births in Orange County, California, Laurent et al33 found a 13%  greater risk of low birth weight per IQR increase (11.5 ppb) in ozone.Three studies35 noted an association of lower socioeconomic status or living in older homes, near roadways, or in urban cores to with increased risk.Thirteen studies reported the association of racial/ethnic disparities with increased risk of low birth weight among mothers in minority groups; 12 were cohort studies, and 1 was a case-control analysis. As with preterm birth and air pollutants, the most frequently noted high-risk subpopulation was black mothers in 10 of 13 studies (77%); 4 (31%) noted higher risks among Asians, and 3 (23%) among Hispanics. Three other studies36 raw birth weight, gestational age Z scores,38 or small for gestational age.23 All studies analyzed PM2.5, and 2 added ozone.36 One study of PM2.5 exposure did find a significant association with low birth weights in 1 subpopulation: –0.42 raw birth weight, gestational age Z score  per IQR for male infants of obese mothers.38Three cohort studies and 1 case-control study showed no associations with low birth weight,2.5 and/or ozone with stillbirth of stillbirth associated with high exposure during the third trimester. The studies of prenatal ozone exposure either during the whole pregnancy, the third trimester, or the week before delivery identified a range of increased risk of stillbirth from 3% to 39%.42 A cause-specific analysis by Ebisu et al39 found the highest risk of 23%  for fetal growth–related stillbirths in association with PM2.5 whole-pregnancy exposure per IQR increase (7.23 μg/m3).For PM40 and Hispanic mothers.42 In an analysis of 12 clinical sites across the US by Mendola et al,40 mothers with asthma were found to be especially susceptible to stillbirth if exposed to whole-pregnancy elevated PM2.5. A report of ozone exposure42 using statewide data from California found Hispanic mothers to be at higher risk from whole-pregnancy 10-ppb increases at mean (SD) levels of 48.48 (12.48) ppb.Two cohort studies noted subpopulations at higher risk: mothers with asthma43 noted no association of stillbirth per trimester or whole pregnancy with prenatal PM2.5 exposures, although it did find a significant association of stillbirth with prenatal exposure to carbon monoxide, nitrogen dioxide, and sulfur dioxide; ozone was not included. Of note, an analysis by Green et al42 of ozone and PM2.5 exposure in California did not detect a significant association of stillbirth per 10 μg/m3 of PM2.5 with whole-pregnancy exposure.One study from New JerseyThere were 5 included studies evaluating the association of maternal exposure to heat with preterm birth  in California noted an increased risk of preterm birth for each 5.6 °C-increase in temperature, as did another study covering 12 clinical sites across the US for 2.8 °C increase.47Three studies46 found an association of racial/ethnic disparity and heat exposure with an increasing risk of preterm birth; higher risk was found among black mothers. Increased risk of preterm birth was also found for Asian mothers and younger mothers in Basu et al.46Two reports from California48 satellite-based spatial modeling technique in Massachusetts found no association with preterm birth  and a small reduction in gestational age at delivery  per 2.8 °C whole-pregnancy mean ambient temperature increase. Of note, standard monitoring data with similar elevated temperatures showed an association with preterm birth .One cross-sectional analysis did not identify a significant association with preterm birth and heat exposure. Kloog et al’s50 Heat was reported as a range of mean apparent temperature49 or as greater than 95% for a specific location and period to account for acclimatization.50There were 3 included studies evaluating the association of maternal exposure to heat with low birth weight  increased risk of low birth weight per 5.6 °C exposure in the third trimester and 13%  for whole pregnancy. The analysis of Ha et al50 of 12 clinical sites across the US showed that ambient local temperature greater than 95% was associated with a relative risk of low birth weight of 1.31  for third-trimester exposure and 2.49  for the whole pregnancy.Each study identified a specific risk in the third trimester; Basu et al48of 459 019 live births in Massachusetts, there was a 16.7-g (3.7-29.7–g) weight reduction at term per IQR increased temperature (8.4 °C) in the third trimester; low birth weight was not significantly increased per 2.8 °C increase in whole pregnancy temperature.In the analysis by Kloog et al50 found that extreme cold (<5%) exposures during second and third trimesters and the whole pregnancy were also significantly associated with low birth weight at term. Ha et al52 Heat was reported per 5.6°C of warm season mean apparent temperature,52 and Ha et al51 measured associations of both mean temperature in the week before delivery and extreme temperature, defined as either greater than 90% or less than 10% of ambient temperature exposure during the whole pregnancy.There were 2 studies evaluating the association of maternal exposure to heat with low birth weight, and both found an increased risk . The nationwide study by Ha et al51 reported an increase of 6% per 1.0 °C in the week before delivery during the warm season; in both studies the authors accommodated for an estimated 1 week from exposure to fetal expulsion. Both studies52 noted higher risks for younger or older mothers and minority racial/ethnic groups; one each indicated poorer outcomes for black or Hispanic mothers.In a case-crossover analysis in California, Basu et al2.5, ozone, and heat exposure with the adverse obstetrical outcomes of preterm birth, low birth weight at term, and stillbirth. More than 32 million births were analyzed, with a mean (SD) of 565 485 (783 278) births per study. In each analysis of climate change–related exposure and adverse obstetrical outcome, most of the studies found a statistically significant increased risk  focusing solely on US populations and is the first, to our knowledge, to combine the increasingly common exposures of air pollutants and heat associated with a series of adverse obstetrical outcomes. Our findings are consistent with other review articles that were not included in our analysis . Reviews that examined PM60 Regarding preterm birth, mechanisms that implicate toxic fine particulates include maternal hematologic transport of inhaled noxious chemicals, the triggering of systemic inflammation, or alterations in function of the autonomic nervous system.63 Low birth weight may be associated with air pollutants by direct toxic effects from fetal exposure, altered maternal cardiac or pulmonary function, systemic inflammation from oxidative stress, placental inflammation, altered placental gene expression, or changes in blood viscosity; multiple effects may operate simultaneously.68 Mechanisms for the association of air pollutants with stillbirth may involve alterations in oxygen transport, DNA damage, or placental injury.72 The cause-specific analysis by Ebisu et al39 of stillbirths reinforces the apparent association of injury to the fetal-placental unit with air pollutant exposure compared with other possible causes.The adverse obstetrical outcomes examined in this study are known to be complex, heterogeneous, and multifactorial in origin; several animal studies suggested that both air pollutant and heat exposure may contribute to adverse obstetrical outcomes.74; it may also trigger preterm premature rupture of membranes and thus preterm birth during the warm season.75 Likewise, heat exposure may impair fetal growth by reducing uterine blood flow and altering placental-fetal exchange.77 Mechanisms associated with elevated temperatures and stillbirth include the initiation of premature labor (as noted above), lowering amniotic fluid volume, damaging the placenta,78 or causing abruption.79Heat exposure may contribute to prematurity through labor instigation from dehydration (via prostaglandin or oxytocin release), from altered blood viscosity, and/or by leading to inefficient thermoregulation80 of preterm birth rates in California before and after coal power plant closures showed a 27% reduction during the 10-year period after closure. Currie et al81 found that among 1.1 million live births in Pennsylvania, the risk of low birth weight was higher within 3 km of a fracking site compared with the background risk and increased by 25% within 1 km of a site.Biologic plausibility is further supported by other recent studies not included in this review. The study by Casey et al2.5 exposure during gestation.40 Among racial/ethnic groups, our findings suggest that black mothers are at greater risk for preterm birth and low birth weight. Social determinants of health, including residence in urban areas with higher exposure to air pollutants and long-term high levels of stress, are known to contribute to adverse obstetrical outcomes.82 A recent study83 from California suggested that PM2.5 exposure alone was associated with an equivalent amount of the racial disparity (black vs white) in preterm birth rates as did other demographic and social factors. Our research suggests that these environmental exposures further exacerbate that background risk and could be included among these social determinants.This review revealed a disproportionate effect on populations defined as pregnant women with certain medical conditions or specific race/ethnicities. Women with asthma may be particularly susceptible to adverse outcomes, such as preterm birth and stillbirth, in association with PM84 was included in the greatest number of studies showing a positive association (13), followed by Massachusetts (6), Georgia (5), and Florida (4). The exposures are complex; even within 1 state, the weather patterns, geography, and urbanization may create zones with widely different pollution risks, as shown by Tu et al31 in Georgia.Regarding both air pollutant and heat exposure, associations with adverse birth outcomes were found across the continental US. For example, studies on air pollution and low birth weight found an association in 19 states in the Northeast (10), Southeast (5), Midwest (2), Mountain (1), and West (1) regions. California, known for both high temperatures and unhealthy particulate and ozone levels,86Future research is needed to further identify at-risk populations, high-exposure geographic areas, and effects of seasonality. This ongoing research may be enhanced by improved geographic information systems that can be mapped onto existing US public health databanks such as the Nationwide Inpatient Sample and Kids’ Inpatient Database.Strengths of the study include the considerable sample size and the wide geographic range that includes every region of the US domestic population. Although other reviews have included global analysis, our focus on the US population makes the findings particularly relevant to pregnant women and health care clinicians in the US. Also, in research examining diffuse exposures, such as air pollution and heat, in which pooled analysis across studies is often not feasible, there is merit to tabulating the overall preponderance of observations from varying studies examining the same outcomes.87 locations and sources analyzed,88 and population demographics.35 For heat exposures, results may also be affected by demographics,52 acclimatization, and seasonal effects.50 For both air pollution and heat exposure, different study designs may complicate direct comparison of the data even within a single study.50 In addition, the number of studies on stillbirth is limited.This study has limitations. First, this review covers only observational studies with heterogeneous sources of air pollution and heat exposure as well as diverse methods of measurement. For air pollutant studies, results can vary based on exposure measurement methods,This review suggests that increasingly common environmental exposures exacerbated by climate change are significantly associated with serious adverse pregnancy outcomes across the US. It appears that the medical community at large and women’s health clinicians in particular should take note of the emerging data and become facile in both communicating these risks with patients and integrating them into plans for care. Moreover, physicians can adopt a more active role as patient advocates to educate elected officials entrusted with public policy and insist on effective action to stop the climate crisis.


Increasing worldwide rates of cesarean section are of global concern. In recent years, cesarean births upon maternal request have become a hotly debated issue. Hence, this study aimed to explore maternal reasons for cesarean preference without medical indications.A descriptive qualitative study was conducted, using in-depth interviews with 27 pregnant women who preferred cesarean birth, attending antenatal care in Songklanagarind Hospital from September 2018 to June 2019. Data were analyzed using content analysis.Maternal reasons for cesarean preference were classified into six main categories: fear of childbirth, safety concerns related to health risk perceptions, negative previous birth experiences, positive attitudes toward cesarean birth, access to biased information and superstitious beliefs in auspicious birth dates. Most women had more than one reason for opting cesarean birth.Several reasons for cesarean birth preference have been elucidated. One striking reason was superstitious beliefs in auspicious birth dates, which are challengable for obstetricians to deal with. Obstetricians should explore the exact reasons why women request cesarean birth in order to prevent or diminish unnecessary cesarean births.The online version contains supplementary material available at 10.1186/s12884-020-03525-3. Cesarean section is a lifesaving procedure for mothers and newborns in certain circumstances. It can, however, lead to adverse maternal and fetal outcomes , 2. CurrCesarean section upon maternal request is a hotly debated issue as one of the contributing factors to increased cesarean section rates –8. ThesePrevious qualitative studies in other countries revealed that factors associated with cesarean preference were fear of pain, previous cesarean birth, previous negative birth experiences, multiparity, low education level and higher maternal age –12. A reThis qualitative study was conducted under the research project “Knowledge and attitudes of pregnant women regarding modes of birth”, registered with the Institutional Review Board of the Faculty of Medicine, Prince of Songkla University (REC.61–177–12-4). Written informed consent was obtained from all participants before entry into the study. Participants were purposefully selected from those in the above-mentioned project, who attended antenatal care in Songklanagarind Hospital from September 2018 to June 2019 and indicated that cesarean section was their preferential mode of birth. They were invited to participate and assured with regard to confidentiality and anonymity. Inclusion criteria of the main project were: 1) singleton pregnancy; 2) gestational age ≥ 20 weeks; and 3) no maternal or fetal indications for cesarean section. Exclusion criteria were women who could not read or write or understand Thai language or whose fetuses had obvious anomalies.In-depth interviews were performed to explore the reasons why pregnant women preferred having cesarean birth. Women were individually interviewed by the third author (PM) in the antenatal clinic in a private room using a narrative style, opening with: “Could you please tell me the reasons why you choose to have cesarean birth?” If the concept was not clear, participants were asked to explain in more detail, until the reasons were clarified. The interview guide is available in the Data were analyzed by the first (CS) and second authors (SC) independently, using content analysis including four stages: 1) decontextualization, 2) recontextualization, 3) categorization and 4) compilation . Each auA total of 27 pregnant women underwent in-depth interviews. Age ranged from 24 to 45 years (median 34), with 14 women being nulliparous. Six categories and 14 themes emerged from the analysis Two women had multiple risk factors: medical diseases, advanced age, infertility and maternal perception of a big baby, leading to the preference of cesarean birth.“I have been married for 6 years, and never got pregnant. Now, I am having my first pregnancy by IVF, after 3 attempts. I am now 45 years old, and also have diabetes mellitus arising during pregnancy, furthermore I am on diet control as well as insulin injections to control blood sugar. I fear that my baby is big at the time of delivery, so I am afraid that my baby will not be safe during vaginal delivery.”Seven women perceived that they had significant risk factors potentially leading to unsafe vaginal birth as well as fetal jeopardy. These included underlying medical diseases , biological risks (advanced age and obesity), infertility and even the perception of a big baby as a consequence of maternal diabetes mellitus. They believed that they were not healthy and might not have enough power to push the baby out, thus resulting in injury to the baby.“My first baby was delivered by vacuum extraction with much difficulty. His head was swelling, though it recovered a few days later. I don’t want to have this problem again.”“I have had a bad experience of my previous pregnancy. I delivered with much difficulty, having labor pain for 2 days and was referred to the provincial hospital for cesarean section. However, cesarean section was not performed as expected. I was given drugs to enhance uterine contractions for such a long period with terrible pain, though ended up with successful vaginal delivery.”Previous negative birth experiences also had a strong impact on pregnant women. Traumatic birth leads to fear of giving birth in subsequent pregnancies, as they perceived childbirth harmful for themselves and their babies. Inadequate analgesia during labor is also a problem, resulting in fear of pain during birth.“I feel that cesarean birth is safe for both mother and baby. Blood loss is less than vaginal birth.”“Cesarean birth is faster than vaginal birth.”“Planned cesarean sections are convenient, date and time can be selected, and there is no need to wait for spontaneous labor.“I have a tumor in the womb, and I would like to have it removed at the time of cesarean section.”Many women had positive attitudes toward cesarean birth, appreciating advantages over vaginal birth in terms of convenience, short delivery time without labor pain and so forth. Four women thought that cesarean section was a safe procedure, without terrible pain as compared to vaginal birth, as well as with less blood loss. Four women thought that it was worth to choose cesarean birth for tubal ligation. Women with fibroids, sometimes also wished to have these removed during cesarean section.“My relative struggled with shoulder dystocia. I am afraid that I may have the same problem, so I would like to have cesarean birth.”“My friend told me that she had cesarean section with a spinal block, and it was not painful.”Currently, people can access various sources of information very easily, including social media, such as Facebook, wherein anybody can share experiences, ideas or comments, and this may have an influence on women’s decisions. Information from television, newspapers or movies may also present some information leading to misunderstanding about the real concepts and factors with regard to mode of birth.“I have read comments shared on Facebook and the internet, saying that vaginal birth is very painful.”“I have searched for information about cesarean section, it is an alternative route of delivery with a short, painful period.”Women have obtained information from either personal advice or mass media. Personal resources including words, experiences or advice from people, such as friends or relatives about their negative or positive birth experiences, may have had an influence on their decisions.“I prefer cesarean birth because I can set an auspicious time for my baby.”Three women believed in destiny. If their babies could be born on an auspicious date and time, they will be prosperous. This is a strong ideology in some families and cesarean birth has an advantage due to this issue.Several reasons were revealed by women who preferred cesarean birth. Fear of childbirth, safety concerns related to health risk perceptions, previous negative birth experiences, positive attitudes toward cesarean birth, access to biased information and superstitious beliefs in auspicious birth dates were found in this study.Almost all aspects were in accordance with previous studies, except for the personal superstitious belief in auspicious birth dates, which has been found only in some Asian countries  –13, 15. Fear of childbirth was the most common reason for cesarean birth preference, which was similar to previous studies , 15, 16.Previous studies reported that negative birth experiences have been recognized as a strong factor for cesarean preference –12, 17. One important factor is related to positive attitudes toward cesarean birth, which may be related to lack of health literacy. Women appreciated the advantages of cesarean birth in terms of convenience, short delivery time and less pain. Some women believed that the procedure to be safe and lacked knowledge with regard to serious complications in subsequent pregnancies. Knowledge has an influence on attitudes and with correct knowledge attitudes might change . Most woInformation from mass media could dictate one’s ideas or beliefs . PerceptFinally, a striking reason in our study was superstitious beliefs in auspicious birth dates. To our knowledge, this cultural preference is not found in most western populations, although superstitious beliefs in auspicious dates and times of birth is quite common in Thai society, as well as Chinese families. A study in California found a large number of Chinese births on the auspicious dates of the 8th, 18th and 28th day of the month, but no corresponding increase among Whites . In ChinOur qualitative study contributed data from pregnant Thai women, reflecting cultural preferences in Thailand with a different culture from that of western countries. It is a challenge for obstetricians to approach, since such ideas and belief systems are difficult to change. Such beliefs may not be related to education level, whereas family backgrounds seem to be more influential.Strength of this study was that two investigators performed the content analysis independently and then discussed results to obtain consensus. This increases study validity, because it is obvious that different researchers may have disparate conclusions from the same data. The two investigators have different professional backgrounds (nurse and obstetrician), so that our findings were approached and discussed from different angles to ensure consistency in the analysis.Previous studies have reported reasons which were not found in our study, such as fear of pelvic floor injury and urinary problems or encouragement from health personnel , 15. SinMany reasons for cesarean birth emerged from pregnant Thai women. One striking reason was superstitious beliefs in auspicious birth dates, which was a challenge for obstetricians to approach. Obstetricians should explore in detail why women request cesarean birth and provide effective counseling in order to decrease cesarean birth on demand.Additional file 1. Interview guide for in-depth interviews.


Several epidemiological studies have examined the possibility of a relationship between season of birth and atopic dermatitis (AD) and food allergy (FA), yet their results are contradictory. We investigated the association between season of birth and risk of AD and FA in Japanese infants.Study subjects were 612 newborn infants born at a single obstetric/pediatric clinic without perinatal diseases. Season of birth was classified as spring (March–May), summer (June–August), autumn (September–November) or winter (December–February). AD was diagnosed according to the United Kingdom Working Party’s criteria. FA was defined as present if there was a history of immediate allergic symptoms within 2 h after ingestion of a food. Specific IgE to the corresponding food was also assessed to support the diagnosis. We assessed the association between season of birth and risk of AD and FA using Cox proportional hazard models.We identified a total of 365 cases of AD occurring during 3659 person-months of follow-up. Compared with summer birth, autumn, winter, and spring birth were significantly positively associated with the risk of AD: adjusted HRs (95% CIs) were 2.67 (1.96–3.63), 1.42 (1.03–1.95), and 1.43 (1.04–1.98), respectively. We identified a total of 23 cases of physician-diagnosed FA occurring during 6815 person-months of follow-up.Being born in the summer is associated with a lower risk of AD compared to other seasons of birth. The low incidence of FA in our cohort group made it difficult to establish a valid association between FA and season of birth as the statistical power was low. The prevalence of atopic dermatitis (AD) continues to increase worldwide; it is already the most common chronic inflammatory skin disease in childhood , 2. GenePrevious studies have examined the association between season of birth (SoB) and AD in infants, children, and adolescents –13. In aRecently it has been proposed that severe AD in infancy might be a risk factor for the subsequent development of food allergy (FA), because food allergens may penetrate via antigen-presenting cells in eczematous skin –16. SeveNot only children with AD and FA but also their family members have a lower quality of life due to food and social restrictions related to avoidance of allergens and financial costs of care , 23. ClaThis study was a retrospective, single-center, hospital-based birth cohort study. We collected information on all babies who were born in an obstetric/pediatric clinic located in a rural area in Mie Prefecture on the main island of Japan, who were born without perinatal diseases between 1 September 2013 and 31 August 2014 and whose mothers visited the clinic for a routine health checkup 1 month after birth. At this clinic, infants receive health check-ups or vaccinations at 1, 2, 3, 4, 5, 7, 10, and 12 months after birth. At each of these visits they were also checked for eczema and FA.We obtained data on gestational age, birth weight and length, birth month, sex, mode of delivery, number of older siblings, presence of eczema, extent of eczema, AD, use of emollients, breast feeding (exclusive breast feeding or mixed feeding or exclusive cow’s milk formula feeding), intake of complementary food , food elimination, food sensitization, food-induced symptoms and FA from medical records. Each infant’s SoB was classified as spring (March–May), summer (June–August), autumn (September–November) or winter (December–February). We defined AD according to the United Kingdom Working Party’s criteria . FA was Person-months were counted from birth until the age in months at the first diagnosis with an outcome under study (AD or FA) or at the end of the follow-up period (maximum 12 months of age), whichever came first. We used Cox proportional hazard models to assess the association between SoB and AD or FA in children. In the analysis for AD, the multivariate hazard ratios (HRs) were adjusted for sex , birthweight , older siblings (0 or ≥ 1), cesarean section (yes or no), and use of emollients at 1 month of age (yes or no). In the analysis for FA, we adjusted for sex , birthweight , older siblings (0 or ≥ 1), atopic dermatitis at 1 month (yes or no), and use of emollients at 1 month of age (yes or no). All statistical analyses were performed using the SAS software package version 9.4 . Two-sided p-values < 0.05 were considered statistically significant. The study protocol was approved by the Ethics Committees of Mie National Hospital.We identified a total of 365 cases of AD occurring during 3659 person-months of follow-up . We also identified a total of 23 cases of physician-diagnosed FA occurring during 6815 person-months of follow-up , including 11 hen’s egg, 8 milk, 1 wheat, 2 soybean and 2 fish allergies. One infant had both a soybean allergy and a fish allergy. Of the 23 children with FA, 19 had positive specific IgE. Although two cases had negative specific IgE and the test was not available in one case of fish allergy and not performed in one case of hen’s egg allergy, all 23 subjects exhibited immediate allergic symptoms after sole ingestion of the food. The characteristics of the study population are provided in Table Crude and adjusted HRs and 95% confidence intervals (CIs) for AD or FA in children in relation to SoB are shown in Table The present study found that, compared with summer birth, autumn, winter, and spring birth were significantly positively associated with the risk of AD. On the other hand, there was no association between SoB and risk of FA.A cross-sectional study in 14,669 Japanese schoolchildren aged 7–15 years showed that being born in autumn or winter was positively associated with the prevalence of eczema before 6 months of age . AnotherThe underlying mechanisms of the association between SoB and AD have not yet been clarified. DNA methylation has been reported as one possible mechanism, given that DNA methylation patterns in the whole blood suggest that seasonal exposures might cause epigenetic changes in immune responses . As newbOur study has several strengths. First, we used data from medical records retrospectively, which prevented recall bias. Second, our outcome definition for FA was based on pediatrician diagnosis, whereas that for AD was based on the UKWP diagnostic criteria. This prevented overestimation of FA and AD which can occur with parent-reported data , 31.Our study has some potential limitations. Because the present study was limited to one clinic in a rural area of Japan, our findings are not applicable to the general population. In addition, the observation period was relatively short. Our definition of FA was based on physician diagnosis in response to a history of immediate objective allergic symptoms after ingestion of a food. We did not perform oral food challenges on children whose parents had eliminated suspected foods from their diets. It is possible that misclassification of outcome occurred. However, such misclassification of outcome is likely to be non-differential, that is, to be similar across exposure categories, and would tend to reduce the observed associations. Further, we were not able to confirm diagnosis of FA in four subjects with negative sensitization to their suspected foods as their parents did not consent to an oral food challenge because of the risk of anaphylaxis. In a sensitivity analysis excluding these four subjects, however, the results were similar to those in the original analysis. In the present study, the number of subjects who developed FA was small, leading to low statistical power. Statistical power calculation revealed that a sample size of 7104 subjects (370 events) would allow us to detect an association between SoB and the risk of FA for a HR 0.64 with a power of 80%. Because the low statistical power of the present analysis prevents a statistically valid conclusion, we could not suggest a valid association between FA and SoB in this study. Finally, although we did control for several potential confounding factors, our results remain confounded by unknown or residual factors.To our knowledge, this is the first report to examine the association between FA defined according to a physician’s diagnosis and SoB in Japanese infants. We found that, compared with summer birth, spring, autumn, or winter birth increased the risk of AD in Japanese infants, while the low incidence of FA in our cohort group made it difficult to establish a valid association between FA and season of birth as the statistical power was low. Further epidemiological research is needed to accumulate evidence on the association between SoB and AD and FA in addition to clarifying the mechanisms underlying these relationships.


To examine health care practitioners’ views of the support women, partners, and the couple relationship require when affected by birth trauma, barriers to gaining such support, and potential improvements.Ongoing distress following psychologically traumatic childbirth, also known as birth trauma, can affect women, partners, and the couple relationship. Birth trauma can lead to post traumatic stress symptoms (PTSS) or disorder (PTSD). Whilst there is a clear system of care for a PTSD diagnosis, support for the more prevalent experience of birth trauma is not well-defined.An online survey of health care practitioners’ views of the support parents require for birth trauma, barriers to accessing support, and potential improvements. Practitioners were recruited in 2018 and the sample for the results presented in the article ranged from 95 to 110.Practitioners reported differing needs of support for women, partners, and the couple as a unit. There was correlation between practitioners reporting having the skills and knowledge to support couples and feeling confident in giving support. The support most commonly offered by practitioners to reduce the impact on the couple relationship was listening to the couple. However practitioners perceived the most effective support was referral to a debriefing service. Practitioners observed several barriers to both providing support and parents accessing support, and improvements to birth trauma support were suggested.Practitioners indicate that some women, partners, and the couple as a unit require support with birth trauma and that barriers exist to accessing effective support. The support that is currently provided often conflicts with practitioners’ perception of what is most effective. Practitioners indicate a need to improve the identification of parents who need support with birth trauma, and more suitable services to support them. Whilst the term birth trauma lacks universal acceptance or standard definition  guided by the National Institute for Health and Care Excellence (NICE). NICE recommend that practitioners offer advice and support to women who report birth as traumatic and consider that their partner may also be affected and require help NICE, . Where pet al., et al., et al., et al., et al., et al., et al., When tailored to meet the needs of post-partum women, trauma-focussed psychological therapies have been shown to be effective in reducing PTSD symptoms in the early post-partum period  and organisations such as the Institute of Health Visiting; NCT; Midwives Information and Resources Service (MIDIRS); and the Royal College of General Practitioners. Recruitment information enabled practitioners to link to and download the participant information sheet. Participation was voluntary and anonymous and to participate, practitioners were required to give consent at the start of the survey hosted by Qualtrics. Contact information in the form of an email was only collected if the participant indicated they wished to receive a summary of the study findings. Data were collected and stored within the web-based survey tool Qualtrics and exported to the statistics software SPSS 25 for analysis.Geographical data was checked and any participants from outside the UK were removed from the sample. The sample was examined using frequencies for practitioner role and length of qualification. Frequencies were calculated for statements about perceived support needs for women, partners, and couples plus practitioner knowledge, skills, and confidence with birth trauma support. Kendall’s tau-b correlations were used to assess relationships between responses to parents’ support needs and practitioner aptitude.Frequencies were calculated for the support practitioners currently offered to couples and which support practitioners viewed as most effective for reducing the impact on the couple relationship. Fisher’s exact tests were used to examine differences between the support offered to couples, and practitioner’s perception of its effectiveness. The frequencies with which practitioners signposted women, partners, and couples to other organisations were calculated. Practitioner’s views of the barriers to couples accessing support, and practitioners providing couples with support were examined using frequencies.Open question responses for practitioners’ views on gaps in support services for couples affected by birth trauma, what would help couples access suitable support, and enable practitioners to support couples affected by birth trauma, were analysed using an approach similar to content analysis. For each question, participant responses were coded, and related codes grouped into categories. Due to apparent similarities, categories were compared between questions and rationalised to form over-arching themes for the open question data collectively.et al., A sample of 202 health care practitioners engaged in the study and their characteristics are given in prior publication of study findings (Delicate n = 60) of ‘women want me to support them’ with birth trauma ‘a lot’ or ‘a great deal’. Compared to 6.5% (n = 7) of ‘partners want me to support them’ and 19.1% (n = 21) of ‘couples want me to support them’ with birth trauma ‘a lot’ or ‘a great deal’. A strong positive correlation was found between practitioner responses to ‘I have the skills and knowledge required to support couples’ and ‘I feel confident in supporting couples’ . Moderate positive correlations were found between practitioner responses to ‘I have the resources to offer support to couples’ and ‘I feel confident in supporting couples’ , and ‘I have the resources to offer support to couples’ and ‘I have the skills and knowledge required to support couples’ .Practitioners reported differing levels of need for support from women, partners, and couples, which are detailed in Table n = 104), then referral to a birth listening/debriefing service , then self-help for example books and websites . Conversely, the support practitioners felt was most effective in reducing the impact of birth trauma on the couple relationship was birth listening/debriefing service , then listening to the couple , then referral to a mother and baby unit . There were significant differences between practitioner’s rate of offering support and rating it most effective support in reducing the impact on a couple’s relationship for: watchful waiting; listening to the couple; self-help; and charitable/third sector organisations .Data for the birth trauma support offered by health care practitioners is detailed in Table n = 73) selected three support types, over a quarter  selected five or more choices. Of the practitioners (n = 22) that indicated ‘other’ as a form of support, 31.8% (n = 7) stated that rewind therapy was offered, six of those seven practitioners indicating they thought rewind therapy was most effective in reducing the impact on the couple relationship.When indicating which type of birth trauma support they felt was most effective, two thirds of practitioners , PANDA , Children Centre , Relate ; and MIND . In open text responses to ‘other’ referrals were: local perinatal mental health charities (n = 12); birth afterthoughts (n = 4); rewind therapy (n = 3); Fatherhood Institute (n = 1); emotional freedom therapy (n = 1); and the GP (n = 1).Referral to other organisations, presented in Table ‘a lot’ or ‘a great deal’ were: ‘long waiting times for support services’ ; ‘stigma around disclosing problems with couple relationships’ ; and ‘lack of suitable services’ . The three most commonly reported barriers to practitioners providing support to couples that practitioners reported experiencing ‘a lot’ or ‘a great deal’ were: ‘absence of suitable service to refer couple to’ ; ‘lack of time to spend personally supporting parents’ ; and ‘lack of contact with partners to identify those with birth trauma’ .Table ‘stigma around disclosing mental health problems’ and ‘stigma around disclosing problems with couple relationship’ as barriers to parents accessing support . Exploring barriers to practitioners providing support, a positive correlation was seen between rating of ‘lack of contact with mothers to identify those with birth trauma’ and ‘lack of contact with partners to identify those with birth trauma’ .A strong positive correlation was found between practitioners’ rating of ‘what are the gaps in support services for couples affected by birth trauma’ (n = 84); ‘what would help couples access suitable support for birth trauma’ (n = 77); and ‘what would help practitioners to support couples affected by birth trauma’ (n = 73). Theme 1) raising awareness and knowledge of birth trauma, 2) prevention of birth trauma 3) identifying those in need of support with birth trauma, and 4) need for suitable birth trauma support. These four themes for potential improvements to birth trauma support are presented with supporting data in Table Four themes emerged from the responses to questions about practitioners’ views on: Theme 1, raising awareness and knowledge of birth trauma, was highlighted as important for both parents and practitioners. Within this theme was a need to improve information to parents and enhanced training for practitioners in how to support couples with birth trauma. Theme 2 was prevention of birth trauma, which was identified as possible through improvements to intrapartum care to ensure care is respectful and based on informed consent. Likewise, improvements to mental health care could enable secondary prevention of PTSD after birth trauma.Theme 3 was identifying those in need of support with birth trauma. This was highlighted as possible through practitioners having more time to spend with parents and continuity to build a relationship, particularly with partners. Similarly, increased communication between practitioners was reported as a potential facilitator to recognising parents in need of support, as was having an effective birth trauma assessment tool. Theme 4 was the need for suitable birth trauma support. Practitioners expressed the need for clearer referral pathways to specialist services that can address differing levels of birth trauma distress. Such support needing to be available in a timely way and be accessible by women, partners, and couples.The findings presented in this paper aimed to examine health care practitioners’ views of the support women, partners, and the couple relationship require when affected by birth trauma, barriers to gaining such support, and potential improvements. Perception of support needs varied according to whether it was for the women, partners, or the couple as a unit. The most offered support was practitioners listening to parents, followed by referral to birth debriefing, and signposting to self-help. Findings highlighted potential barriers to getting birth trauma support along with insight of possible improvements.et al., et al., et al., Results suggest that practitioners see less demand for birth trauma support from the couple as a unit, or partners, compared to women. Conversely, practitioners highlighted lack of contact with partners as a barrier to providing birth trauma support, and a potential improvement being enhanced services for partners. Further indications that perinatal health services need to consider the needs of partners (Burgess and Goldman, et al., et al., et al., Despite no conclusive evidence for the routine use of birth debriefing (Bastos Similarly, the current study found some practitioners referring to rewind therapy which is not currently an evidenced-based PTSD treatment NICE, b. Howeveet al., et al., Likewise, widespread referral to self-help reported by practitioners in the survey could be due to a lack of suitable services to refer to, or long waiting lists for receiving treatment (Thomson and Garrett, et al., et al., et al., Reported barriers to practitioners supporting parents were in concordance with previous research findings: lack of time to spend with parents (Noonan et al., et al., et al., Developed from the present study results, Figure et al., et al., et al., Knowledgeable practitioners and birth trauma aware health care practitioners could help prevent birth trauma. In the antenatal phase prevention can result from assessing and dealing with prior mental health vulnerability and enabling effective birth preparation (Simpson et al., et al., Whilst reassurance and a watch and wait approach is suitable in the early weeks post-partum NICE, a, the cuThe main limitation of the present study is the use a self-selecting convenience sample which is not representative of the range of post-partum health care practitioners working with parents. Sample size was relatively small and low participant rates from some practitioner groups means their perspective is under-represented in the findings. Study results should be construed as exploratory due to the use of an unvalidated survey, practitioners responding retrospectively based on a range of observations of parents but not clinical diagnoses.In contrast, the study findings add to a limited body of evidence of health care practitioners’ perspectives of birth trauma. Results illustrate current practice in birth trauma support, practitioners’ proficiency, and insight into how support may be improved. These findings are important for health care practitioners, service providers, commissioners, and researchers engaged in the perinatal phase. Results also have implications for the development of policy and practice to aid the prevention of birth trauma and the provision of effective support services.Practitioners indicated that some women, partners, and the couple as a unit require support for birth trauma and identified some barriers to accessing effective support. Suggested improvements include preventing birth being perceived as traumatic in the first instance, raising birth trauma awareness in practitioners and parents, and improving identification of those requiring support. The birth trauma support that is currently being offered is often not evidence based and relies on practitioner’s perceptions of effectiveness and/or availability. It is important that further research is conducted into appropriate birth trauma treatments and that services offer evidence-based support to meet the needs of parents as individuals and the couple as a unit.