Cohort Profile: the China-Anhui Birth Cohort Study

Establishing a Multifaceted Comprehensive Maternity Cohort Facilitates Understanding of How Environmental Exposures Impact Perinatal Health

China's "three-child policy", implemented in response to population aging, has made the protection of maternal and infant health an urgent priority. In this environmental and medical big-data era, the Zhejiang Environmental and Birth Health Research Alliance (ZEBRA) maternity cohort was established with the aim of identifying risk factors for perinatal morbidity and mortality from the perspectives of both observational epidemiology and experimental etiology. Compared with conventional birth cohorts, the inclusion of a maternity cohort allows greater scope for research and places an emphasis on maternal health. In particular, it allows us to focus on pregnant women with a history of pregnancy-related illnesses and those planning to have a second or third child. There are currently many pressing issues in perinatal health, including the risk associations between exogenous together with endogenous factors and the occurrence of perinatal abnormalities, pregnancy complications, and adverse pregnancy outcomes. It is crucial to explore the interaction between environmental exposures and genetic factors affecting perinatal health if we are to improve it. It is also worthwhile to assess the feasibility of the early stage prediction of major perinatal abnormalities. We hope to study this in the ZEBRA cohort and also seek nationwide and international collaborations to establish a multicenter cohort consortium, with the ultimate goal of contributing epidemiological evidence to literature and providing evidence-based insights for global maternal and child healthcare.

Maximising the potential of Chinese birth cohort studies: a systematic review of mother-baby cohorts in mainland China

OBJECTIVES

There is now a growing interest in early-life influences on adult diseases in China. A number of birth cohorts have been established. This systematic review provided a better understanding of the development of mother-baby cohorts in China.

STUDY DESIGN

Systematic review.

METHODS

We conducted a systematic review for research or profile papers in English/Chinese that reported data from mother-baby cohorts in mainland China, with ≥1y follow-up after birth. We identified 315 papers, corresponding to 31 cohorts from 19 provinces/megacities.

RESULTS

All cohorts started in 1999-2017 (21 after 2010) and were set up with broad objectives or specific scientific focus. The baseline sample size varied, from <500 to >300,000 mothers. A majority of cohorts were initiated during pregnancy and followed children to <10y, only six to adolescence and none into adulthood. These cohorts mostly collected samples from mothers and babies, in addition to using interviews/questionnaires to collect information about pregnancy, birth and child health. Most cohorts were recruited from a single province/city. The large western region was understudied.

CONCLUSIONS

Mother-baby cohorts have developed rapidly in China, but usually with a short follow-up duration. Extending the follow-up of children and developing cross-cohort collaboration will increase the diversity, size and coverage of the sample, allow studying early influences on life-course health and identify targets for early intervention in the Chinese population.

The Born in Guangzhou Cohort Study enables generational genetic discoveries

Genomic research that targets large-scale, prospective birth cohorts constitutes an essential strategy for understanding the influence of genetics and environment on human health1. Nonetheless, such studies remain scarce, particularly in Asia. Here we present the phase I genome study of the Born in Guangzhou Cohort Study2 (BIGCS), which encompasses the sequencing and analysis of 4,053 Chinese individuals, primarily composed of trios or mother-infant duos residing in South China. Our analysis reveals novel genetic variants, a high-quality reference panel, and fine-scale local genetic structure within BIGCS. Notably, we identify previously unreported East Asian-specific genetic associations with maternal total bile acid, gestational weight gain and infant cord blood traits. Additionally, we observe prevalent age-specific genetic effects on lipid levels in mothers and infants. In an exploratory intergenerational Mendelian randomization analysis, we estimate the maternal putatively causal and fetal genetic effects of seven adult phenotypes on seven fetal growth-related measurements. These findings illuminate the genetic links between maternal and early-life traits in an East Asian population and lay the groundwork for future research into the intricate interplay of genetics, intrauterine exposures and early-life experiences in shaping long-term health.

Longitudinal study of multidimensional factors influencing maternal and offspring health outcomes: a study protocol

BACKGROUND

Reducing preventable adverse maternal and offspring outcomes is a global priority. The causes of adverse maternal and fetal outcomes are complex with multidimensional influencing factors. In addition, the Covid-19 epidemic has had a significant psychological and physical impact on people. China is now stepping into the post-epidemic era. We are curious about the psychological and physical situation of maternity in China at this stage. Therefore, we plan to initiate a prospective longitudinal study to investigate the multidimensional influences and mechanisms that affect maternal and offspring health.

METHOD

We will recruit eligible pregnant women at Renmin Hospital of Hubei Province, China. The expected sample size is 1490. We will assess socio-demographics, Covid-19 related information, social capital, sleep, mental health and medical records, including clinical examination and biochemical tests. Eligible pregnant women will be enrolled in the study with less than 14 weeks of gestation. Participants will receive a total of nine follow-up visits between mid-pregnancy and one year postpartum. The offspring will be followed up at birth, 6 weeks, 3 months, 6 months and one year. In addition, a qualitative study will be conducted to understand the underlying causes that affect maternal and offspring health outcomes.

DISCUSSION

This is the first longitudinal study of maternity in Wuhan, Hubei Province which integrates physical, psychological and social capital dimensions. Wuhan is the first city to be affected by Covid-19 in China. As China moves into the post-epidemic era, this study will provide us with a better understanding of the long-term impact of the epidemic on maternal and offspring health outcomes. We will implement a range of rigorous measures to enhance participants' retention rate and ensure the quality of data. The study will provide empirical results for maternal health in the post-epidemic era.

Prenatal Healthy Dietary Patterns Are Associated with Reduced Behavioral Problems of Preschool Children in China: A Latent Class Analysis

The relation between maternal dietary patterns during pregnancy and offspring behavioral problems is less verified. Therefore, we have aimed to assess the relationship between them and have hypothesized that children of mothers with healthy dietary patterns during pregnancy have better behavior. The 1612 mother-child pairs of the China-Anhui Birth Cohort Study (C-ABCS) have been enrolled as the study population. The dietary behaviors of mothers during early and mid-pregnancy have been investigated using a semi-quantitative food frequency questionnaire. Preschool child behavioral problems have been assessed. Clusters of maternal food groups intakes have been identified using latent class analysis, and the association between maternal dietary patterns and child behavioral problems has been subsequently analyzed using logistic regression. Maternal age at inclusion is 26.56 ± 3.51 years. There has been a preponderance of boys (53.3%). Maternal food groups intakes have been classified into four groups: "High-consumed pattern (HCP)", "Southern dietary pattern (SDP)", "Northern dietary pattern (NDP)", and "Low-consumed pattern (LCP)". The offspring with maternal SDP and NDP have lower emotional symptoms compared to the offspring with maternal LCP in the first trimester (p < 0.05). It has been reported to lower conduct problems in children with maternal SDP than the children with maternal LCP in the second trimester (p < 0.05). In boys, we have detected associations between first-trimester SDP and lower emotional symptoms (p < 0.05) and between second-trimester SDP with decreased peer relationship problems (p < 0.05). In girls, total difficulty scores are lower with second-trimester SDP (p < 0.05). Maternal SDP in early and mid-pregnancy predicts reduced behavioral problems in preschool children, while maternal HCP and NDP during pregnancy may result in fewer developmental benefits.

Precision medicine via the integration of phenotype-genotype information in neonatal genome project

The explosion of next-generation sequencing (NGS) has enabled the widespread use of genomic data in precision medicine. Currently, several neonatal genome projects have emerged to explore the advantages of NGS to diagnose or screen for rare genetic disorders. These projects have made remarkable achievements, but still the genome data could be further explored with the assistance of phenotype collection. In contrast, longitudinal birth cohorts are great examples to record and apply phenotypic information in clinical studies starting at the neonatal period, especially the trajectory analyses for health development or disease progression. It is obvious that efficient integration of genotype and phenotype benefits not only the clinical management of rare genetic disorders but also the risk assessment of complex diseases. Here, we first summarize the recent neonatal genome projects as well as some longitudinal birth cohorts. Then, we propose two simplified strategies by integrating genotypic and phenotypic information in precision medicine based on current studies. Finally, research collaborations, sociological issues, and future perspectives are discussed. How to maximize neonatal genomic information to benefit the pediatric population remains an area in need of more research and effort.

Non-Linear and Sex-Specific Effect of Maternal Pre-Pregnancy BMI on Emotional and Behavioral Development of Preschool Children: A Population-Based Cohort Study

(1) Background: The aim was to examine the non-linear and sex-specific outcomes of maternal pre-pregnancy BMI on emotional and behavioral development of preschool children; (2) Methods: This study was based on the China-Anhui Birth Cohort (C-ABCS), including 3648 mother-child pairs. Maternal pre-pregnancy BMI was calculated from the maternal pre-pregnancy height and weight measured at the first antenatal checkup. Main caregivers completed the Strengths and Difficulties Questionnaire (SDQ) to assess children's preschool emotional and behavioral development. A restricted cubic spline model was drawn using Stata version 15.1 to analyze the association between maternal pre-pregnancy BMI and preschoolers' SDQ scores by sex; (3) Results: Among boys, maternal pre-pregnancy underweight was associated with the increased risk of conduct problems and pro-social behaviors, and pre-pregnancy overweight/obesity related with the increased risk of peer problems. Interestingly, when maternal pre-pregnancy BMI was between 18.50 kg/m² and 18.67 kg/m², boys had the increased risk of conduct problems. When pre-pregnancy BMI was between 18.50 kg/m² and 19.57 kg/m², boys had the increased risk of pro-social problems. No significant associations were observed; (4) Conclusions: A non-linear effect of maternal pre-pregnancy BMI on emotional and behavioral development has been found in preschool boys. In particular, pre-pregnancy normal weight may still affect boys' emotional and behavioral development.

The continuing evolution of birth cohort studies: achievements and challenges

Well-designed birth cohorts are able to estimate prevalence/distribution of various health events/outcomes, and to link early-life origins with adult health and function. The past two decades have seen a surge in the establishment of new birth cohorts and their accompanying research. We discussed distinct designs of current birth cohort studies, reviewed their achievements, and highlighted insights obtained from birth cohort studies, as well as challenges we are facing. Birth cohort studies are providing increasing opportunities to identify determining factors for short- and long-term health, yielding substantial evidence to uncover biological mechanisms of diseases and phenotypes, and providing further insights for public health. Dynamic monitoring, accurate measurements, long-term follow-ups and collaborative efforts are warranted in new birth cohorts to elucidate the nature of life course relationships in contemporary generation.

Association of maternal prenatal depression and anxiety with toddler sleep: the China-Anhui Birth Cohort study

Maternal prenatal depression is associated with child sleep. We investigated whether maternal depression comorbid with anxiety worsens toddler's sleep problems in a prospective cohort study. A total of 1583 mother-infant pairs from the China-Anhui Birth Cohort study were examined. The participants completed the Center for Epidemiologic Studies Depression Scale (CES-D) and Self-Rating Anxiety Scale (SAS) at 30-34 weeks of gestation, and the Edinburgh Postnatal Depression Scale (EPDS) at 3-month postpartum. Toddler's sleep was assessed by the Brief Infant Sleep Questionnaire (BISQ) at 30 months old. Logistic regression models were used to investigate the associations between prenatal depression and anxiety and toddler's sleep, while adjusting for maternal gestational age, education, family income, alcohol use, premature birth, fetal growth restriction, mode of delivery, postnatal depression, and 3-month breastfeeding. In total, 9.0% of participants reported prenatal depression comorbid with anxiety symptoms, and the prevalence of depression, anxiety was 6.7% and 7.3%, respectively. Compared with mothers without depression and anxiety, maternal depression combined with anxiety were significantly associated with shorter total sleep duration (11.16 ± 1.06 h), longer settling time (29.25 ± 23.57 min), and higher risk of toddlers' sleep problems assessed by BISQ (OR = 2.09, 95% CI: 1.22-3.57) or parental report (OR = 1.84, 95% CI: 1.22-2.77). However, there was no significant association between maternal postnatal depression and toddler sleep behaviors. Maternal prenatal depression comorbid with anxiety significantly associated with poorer toddler's sleep. Strategies to regulate prenatal mood status should be considered during prenatal health care to improve children's sleep development.

The China birth cohort study (CBCS)

The China birth cohort study (CBCS) is a prospective longitudinal, mega-cohort study and the first national-based birth cohort study, aiming to establish a birth cohort covering representative geographical areas of the whole of China to investigate risk factors for birth defects and develop strategies for their reduction. Pregnant women who are of Chinese nationality, are 6–13⁺⁶ weeks of gestation, plan to attend the routine antenatal examination and deliver in the study site, and give their informed, written consent are eligible to participate in this study. All participants are followed-up through an in-person interview at 20–23⁺⁶ weeks and again at 28–33⁺⁶ weeks of gestation, and at delivery, respectively. CBCS has been divided into three phases from 20th November 2017 to 31st December 2021, and the first two phases have now been completed on 29th February 2020, enrolling 120 377 eligible pregnant women during this period. During the same period a total of 40 837 participants had been followed up to the end of pregnancy. Study recruitment will continue until December 2021 to achieve the target of 500 000 participants. Meanwhile, biological samples including peripheral blood, amniocytes, cord blood, placenta, or umbilical cord tissue have been collected from participants according to various conditions. The incidence of birth defects in this group is 2.5% and congenital heart disease is the most common type of birth defect seen so far. A website is in the advanced stages of planning, to allow seamless data transfer and facilitate collaboration with groups around the world.

Prenatal Bisphenol A Exposure and Early Childhood Behavior and Cognitive Function: A Chinese Birth Cohort Study

INTRODUCTION

Biomonitoring of bisphenol A (BPA) in human blood is still scarce, although already noticeable. We aimed to examine the associations between prenatal serum BPA concentrations and behavior and cognitive function in preschool children.

METHODS

A total of 1,782 mother-child pairs with complete demographic information, blood samples, and psychological measurements were included from the China-Anhui Birth Cohort (C-ABCS). We detected serum BPA concentrations and assessed children's neurodevelopment using a set of psychometric scales.

RESULTS

The median prenatal maternal serum BPA concentration was 0.23 (P25, P75: 0.07, 0.52) ng/mL, with a detection frequency of 85.19%. Compared with the girls with the lowest concentrations, those with highest BPA concentrations had increased risks of inhibitory self-control impairment [relative risk (RR) = 3.66, 95% confidence interval (CI): 1.53, 7.58], emergent metacognition impairment (RR = 1.70, 95% CI: 1.07, 2.78), conduct problem (RR = 1.68, 95% CI: 1.12, 2.39), peer relationship problem (RR = 2.57, 95% CI: 1.33, 4.47), higher total difficulties score (RR = 1.76, 95% CI: 1.12, 2.67), and higher impact factor score (RR = 1.52, 95% CI: 1.11, 2.05), while the boys with the highest prenatal BPA concentrations had an increased risk of conduct problem compared with those with the lowest concentrations (RR = 1.59, 95% CI: 1.09, 2.24) (P-interaction = 0.011). After stratification by age, high prenatal BPA concentrations were associated with increased ADHD (RR = 4.44, 95% CI: 1.54, 10.85) among children aged 3 years, not among children aged 4 years.

CONCLUSION

Our study revealed the sex-specific and age-specific impacts of prenatal BPA exposure on preschool children's cognitive and behavioral development.

The Chinese Adolescent Cohort Study: Design, Implementation, and Major Findings

The importance of diet quality on children's growth is being increasingly recognized. The Chinese Adolescent Cohort (CAC) is a longitudinal cohort study to comprehensively investigate the health impacts of nutritional factors on child growth. From 2013 to 2018, 6,967 children aged 6-8 years have been recruited from 23 primary schools in Sichuan, Guizhou, and Chongqing, which have been planned to be followed up annually until their age of 15 years. Regular assessments included the measurement of height, weight, waist circumference, and skinfold thicknesses; pubertal development was examined by trained investigators according to Tanner stages; dietary intake was obtained by three 24-h recalls and food frequency questionnaire; validated questionnaires were used to estimate socio-demographic characteristics, physical activity, and sedentary behaviors. Findings from the CAC baseline and the first follow-up data suggested that higher protein intake among girls and unhealthy eating habits among children might increase the risk for childhood obesity. Also, higher intakes of grain and meat and lower overall diet quality and intakes of dietary fiber and tuber might be associated with advanced pubertal development. Those results indicated that the CAC study could contribute to the development of strategies for optimizing Chinese children's health.

Maternal selenium deficiency during gestation is positively associated with the risks for LBW and SGA newborns in a Chinese population

BACKGROUND

Maternal selenium (Se) deficiency is associated with some adverse pregnant outcomes. However, it remains controversial whether maternal Se deficiency during gestation enhances the risks for low-birth-weight (LBW) and small-for-gestational-age (SGA) newborns.

METHODS

For our cohort study, total 3133 mother-and-infant pairs were selected. Maternal serum Se concentration was detected by graphite furnace atomic absorption spectrometry. According to international references for maternal serum Se concentration, subjects were divided into Se deficiency (<45.0 μg/L), Se insufficiency (45.0-94.9 μg/L) and Se sufficiency (≥95.0 μg/L).

RESULTS

There was a positive relation of maternal serum Se concentration in gestation and neonatal birth weight. Further analysis showed that the risks for LBW and SGA in SD group were significantly higher than that in SI and SS group, the adjusted ORs for LBW and SGA newborns were 1.87 (95%CI: 1.02, 3.45; P = 0.04) and 1.47 (95%CI: 1.07, 2.02; P = 0.02) in SI group, and 3.92 (95%CI: 2.03, 7.57; P < 0.001) and 2.77 (95%CI: 1.92, 4.02; P < 0.001) in SD group compared to SS group. In different gender subgroup, positive relations were observed between maternal Se deficiency and the risk for LBW girls, as well as the risks for both SGA girls and boys.

CONCLUSION

Maternal Se deficiency in gestation was positively associated with the risk for LBW girls, as well as the risks for both SGA girls and boys.

The role of neonatal vitamin D in the association of prenatal depression with toddlers ADHD symptoms: A birth cohort study

BACKGROUND

Vitamin D has been demonstrated a "neuroprotective" effect, but it is unclear whether early-life adequate vitamin D protect adverse neurodevelopment. We aimed to examine the role of neonatal vitamin D in the association of maternal depression (MD) symptoms with toddlers ADHD.

METHODS

Participants included 1 125 mother-infant pairs from the China-Anhui Birth Cohort study. MD was assessed by the Center for Epidemiological Studies Depression Scale (CES-D) at 30-34 gestational weeks. Toddlers ADHD was reported by the Conners' Hyperactivity Index (CHI) at 48-54 months postpartum. Multiple logistic regression models were performed to evaluate the association of maternal depressive score and toddlers ADHD while cord blood 25(OH)D levels were stratified.

RESULTS

Toddlers of mothers with higher depression score were at higher risk of ADHD (20.1% vs 11.1%, P = 0.003; adjusted RR=1.75, 95% CI: 1.10-2.81). Among toddlers with neonatal vitamin D deficiency (VDD), ADHD risk was significantly increased with maternal MD (adjusted RR=3.74, 95% CI: 1.49-9.41), but the association was not found in toddlers with neonatal vitamin D adequacy (VDA). Compared to toddlers without MD, toddlers with both MD and neonatal VDD had higher risk of ADHD (adjusted RR=3.10, 95% CI: 1.44-6.63). But the risk did not significantly increase in toddlers with MD and neonatal VDA (adjusted RR=1.53, 95% CI: 0.86-2.72).

LIMITATIONS

Maternal depressive symptoms in early pregnancy and anxious symptoms were needed to include.

CONCLUSION

This prospective study indicated that the detrimental effect of maternal prenatal depressive symptoms on offspring's ADHD symptoms strengthened in toddlers with neonatal VDD.

Gender-specific effect of pregnancy-related anxiety on preschooler's emotional and behavioral development: A population-based cohort study

BACKGROUND

Pregnancy-related anxiety plays a major role in shaping offspring's neural development. However, its gender-specific effect on children's emotional and behavioral development is controversial and the knowledge of critical period is limited. This study aims to examine gender-specific effect of pregnancy-related anxiety on preschooler's emotional and behavioral development.

METHODS

This study was based on the China-Anhui Birth Cohort Study (C-ABCS). A total of 3443 mother-child pairs were included in final data analysis. Pregnancy-related anxiety was assessed by Pregnancy-Related Anxiety Questionnaire respectively in the 1^st and 3^rd trimester of pregnancy. Strengths and Difficulties Questionnaires (SDQ) were completed by parents to assess preschool emotional and behavioral development in boys and girls. Logistic regression models were used to examine the association between pregnancy-related anxiety and preschoolers' emotional and behavioral problems.

RESULTS

The overall prevalence of pregnancy-related anxiety was 31.6%. Compared with those whose mothers without pregnancy-related anxiety in either 1^st or 3^rd trimester, preschool boys born of mothers with pregnancy-related anxiety in the 1^st trimester and in the 3^rd trimester had an increased risk of conduct problems. Pregnancy-related anxiety in the 1^st, 3^rd trimester and in both trimesters all related with preschool boys' hyperactivity and total difficult problems. Pregnancy-related anxiety in the 1^st trimester and in both 1^st and 3^rd trimester increased the risk of preschool girls' emotional problems and total difficult problems.

CONCLUSION

Pregnancy-related anxiety may relate with preschool boys' externalizing problems in early and late of pregnancy and increase the risk of internalizing problems in girls in early pregnancy.

LIMITATIONS

There was no data on pregnancy-related anxiety in the second trimester.

Nutrition in Pregnancy and Growth in Southwest China (NPGSC) cohort: Design, implementation, and characteristics

BACKGROUND

Pregnancy and birth cohorts addressing maternal nutrition and its impact on health outcomes have been rare in China, especially in Southwest China.

OBJECTIVES

To describe the design, implementation, baseline characteristics, and initial results of the Nutrition in Pregnancy and Growth in Southwest China (NPGSC) cohort.

POPULATION

Pregnant women with their children in Southwest China.

DESIGN

NPGSC participants have been prospectively recruited since 2014. Pregnant women were invited to participate in the study at their first routine ultrasound examination in gestational weeks 9-11. Data were assessed three times during pregnancy (9-11, 20-22, and 33-35 gestation weeks), and eight times in infants and toddlers.

METHODS

Pre-pregnancy body weight and height were self-reported; gestational weight gain was measured at regular intervals. Both food frequency questionnaires (FFQ) and 24-hour dietary recalls were used to collect dietary intakes during pregnancy, and FFQ for diet before pregnancy. Information on pregnancy outcomes was extracted from the medical birth registry. Anthropometry of children in the first 3 years of life was measured by trained investigators. Other child outcomes, including feeding practices (self-reported by mothers) and cognitive development (assessed by the Chinese version of Ages and Stages Questionnaire), were recorded.

PRELIMINARY RESULTS

Between 2014 and 2018, 12 989 pregnant women were enrolled, and 2296 children completed the 3 years follow-up. Among them, 115 pregnancies ended in stillbirth. Mean maternal pre-pregnancy BMI was 21.1 kg/m² and mean gestational weight gain was 13.5 kg 18.6% of mothers developed gestational diabetes and 1.5% of mothers were diagnosed with preeclampsia. Mean birthweight and birth length of children were, respectively, 3329 g and 49.4 cm.

CONCLUSION

We built a prospective cohort in Southwest China, which can provide valuable data to investigate the relevance of nutrition for the health of mothers and children.

Study Design and Baseline Profiles of Participants in the Tianjin Birth Cohort (TJBC) in China

Background

To investigate the causal link between early-life exposures and long-term health consequences, we established the Tianjin Birth Cohort (TJBC), a large-scale prospective cohort in northern China.

Methods

TJBC aims to enroll 10,000 families with follow-ups from pregnancy until children’s six year-old. Pregnant women and their spouses were recruited through a three-tier antenatal healthcare system at early pregnancy, with follow-ups at mid-pregnancy, late pregnancy, delivery, 42 days after delivery, 6 months after delivery, and each year until 6 years old. Antenatal/neonatal examination, biological samples and questionnaires were collected.

Results

From August 2017 to January 2019, a total of 3,924 pregnant women have already been enrolled, and 1,697 women have given birth. We observed the prevalence of gestational diabetes mellitus as 18.1%, anemia as 20.4%, and thyroid hypofunction as 2.0%. In singleton live births, 5.6% were preterm birth (PTB), 3.7% were low birth weight, and 7.3% were macrosomia. Based on current data, we also identified maternal/paternal factors which increased the risk of PTB, including paternal age (OR 1.07; 95% CI, 1.01–1.14 for each year increase), vaginal bleeding during pregnancy (OR 2.82; 95% CI, 1.54–5.17) and maternal early-pregnancy BMI (OR 1.08; 95% CI, 1.01–1.15 for each kg/m² increase).

Conclusion

TJBC has the strength of collecting comprehensive maternal, paternal, and childhood information. With a diverse range of biological samples, we are also engaging with emerging new technologies for multi-omics research. The study would provide new insight into the causal link between macro/micro-environmental exposures of early life and short/long-term health consequences.

Isolated effect of maternal thyroid-stimulating hormone, free thyroxine and antithyroid peroxidase antibodies in early pregnancy on gestational diabetes mellitus: a birth cohort study in China

This article aims to understand the isolated effect of maternal thyroid-stimulating hormone (TSH), free thyroxine (FT₄) and antithyroid peroxidase antibodies (TPOAb) in early pregnancy on gestational diabetes mellitus (GDM). Based on a birth cohort, pregnant women presented to maternity hospitals for the first antenatal care from Nov 2008 to Oct 2010 were invited to participate in the study. A self-administered questionnaire was asked to complete to collect data on socio-economic variables, previous adverse pregnancy outcomes, method of conception, previous endocrinic and metabolic diseases, and pregnancy-related anxiety in 1^st trimester of the index pregnancy. Pre-pregnancy BMI was measured. Serum samples were collected, and TSH, FT₄ and TPOAb were assayed. GDM was confirmed from medical records screened on 24-28 gestational weeks by using oral glucose tolerance test (OGTT). The prevalence of isolated subclinical hypothyroidism, hypothyroidemia and positive TPOAb in early pregnancy was 2.0%, 2.0% and 12.8%. Prevalence of GDM in women with the isolated sub-clinical hypothyroidism, hypothyroxinemia and positive TPOAb was 2.9%, 2.8% and 3.1%, respectively, which were all higher than that detected in euthyroidism women (1.2%). Women with isolated positive TPOAb had significantly higher TSH and lower FT₄ level compared with euthyroidism women. It was found that isolated positive TPOAb in early pregnancy increased the risk of GDM, adjusted RR and 95%CI being 2.541(1.037-6.226). No significant relationships were identified between isolated sub-clinical hypothyroidism or hypothyroxinemia with GDM. In conclusion, isolated thyroid autoimmunity, represented by positive TPOAb, in early pregnancy were associated with GDM independent of TSH and FT₄.

Elective caesarean section on maternal request prior to 39 gestational weeks and childhood psychopathology: a birth cohort study in China

BACKGROUND

The recommendation of non-indicated caesarean section (CS) after 39 gestational weeks has been announced based on evidence of maternal and infant physiological effects. The potential psychological risks have not been acknowledged. This study aims to investigate emotional and behavioral problems in pre-school children born with elective CS (ECS) on maternal request prior to 39 weeks.

METHODS

Pregnant women within 12 gestational weeks between November 2008 and October 2010 were invited to participate in the China-Anhui Birth Cohort Study (C-ABCS). They were asked to complete a self-administered questionnaire respectively in 1st and 3rd trimester of pregnancy to collect basic maternal characteristics. Pregnant complications and delivery modes were abstracted from medical notes. Their singleton live births were followed up at preschool age. Strengths and Difficulties Questionnaires (SDQ) were completed by parents to assess children's emotional and behavioral problems. A total of 3319 mother-child pairs were put into the final analysis. Descriptive analysis and binary logistic regression analysis were used to assess the impact of delivery modes on abnormalities in SDQ dimensions at various gestational ages.

RESULTS

The prevalence of ECS on maternal request prior to 39 weeks, at 39-40 weeks, and after 41 weeks was 16.6, 23.7 and 15.9%, respectively. Compared with those born vaginally, children born with ECS on maternal request were more likely to have total difficult problems (RR 1.519, 95% confidence interval 1.077 to 2.142). ECS on maternal request was the independent predictor of emotional problems (3.479, 1.676 to 7.222) and total difficult problems (2.172, 1.175 to 4.016) in children born prior to 39 gestational weeks.

CONCLUSION

Children delivered by ECS on maternal request have an increased risk to have emotional and behavioral problems prior to 39 gestational weeks at preschool age. The potential psychological implication prior to 39 weeks has been added to the roster of impacts of ECS on maternal request. Further research is needed to probe the potential biological mechanisms.

Current Recommended Vitamin D Prenatal Supplementation and Fetal Growth: Results From the China-Anhui Birth Cohort Study

CONTEXT

Maternal vitamin D insufficiency has been associated with fetal growth restriction. However, the effect of maternal vitamin D supplementation on fetal growth has not been confirmed.

OBJECTIVE

To assess the effect of maternal vitamin D supplementation recommended by the Institute of Medicine (IOM) during pregnancy on the neonatal vitamin D status and the risk of small for gestational age (SGA).

DESIGN AND PARTICIPANTS

As part of the China-Anhui Birth Cohort study, maternal sociodemographic characteristics, food intake, lifestyle, information on vitamin D supplementation, and birth outcomes were prospectively collected. For participants, 600 IU/d of vitamin D3 was routinely advised to take during pregnancy. Cord blood levels of 25-hydroxyvitamin D [25(OH)D], calcium, and phosphorus were measured in 1491 neonates who were divided into three groups based on the duration of maternal vitamin D supplementation during pregnancy.

RESULTS

Mean cord blood concentrations of 25(OH)D were 3.5 nmol/L higher [95% confidence interval (CI), 0.8, 6.2] in neonates (median, 37.9 nmol/L) whose mother took vitamin D supplementation for >2 months during pregnancy compared with those (median, 34.3 nmol/L) whose mother did not take any supplement. These significant differences on cord blood concentrations of 25(OH)D occurred regardless of the season of birth. The adjusted risk of SGA in pregnant women with vitamin D supplementation for >2 months was significantly decreased than that in women without any vitamin D supplementation (11.8% vs 6.9%; adjusted odds ratio = 0.53; 95% CI, 0.32, 0.87).

CONCLUSIONS

The findings from China suggest that maternal vitamin D supplementation recommended by the IOM results in a slight but significantly higher fetal level of 25(OH)D and improves fetal growth.

Effects of Prenatal Phthalate Exposure on Thyroid Hormone Concentrations Beginning at The Embryonic Stage

Limited studies have consistently shown an association of phthalates exposure with thyroid hormones (THs) in pregnant women. However, it remains unknown on which specific phthalates can affect THs and whether any effects could differ by gestational age. In the present study, we investigated associations between serum concentrations of phthalate monoesters [monoethyl phthalate (MEP), mono-(n + iso)-butyl phthalate (MBP) and mono(2-ethylhexyl) phthalate (MEHP)] and THs [thyroid-stimulating hormone (TSH), total thyroxine (TT4) and free thyroxine (FT4)] in Chinese pregnant women. 1,397 women were recruited from the China-Anhui Birth Cohort. Maternal serum samples were collected and used to measure phthalate metabolites and THs. Covariate-adjusted linear regression analyses showed that natural log (Ln)-transferred concentrations of MBP and LnMEHP were negatively associated with TT4 (β = −0.277 and –0.461, respectively; p < 0.001). Stratification analyses by gestational weeks showed significant associations of LnMBP and LnMEHP with TT4 in gestational weeks 5 to 8, 9 to 12, and 13 to 20. Our findings suggest an association of serum phthalates with lower TT4. The influence of MBP and MEHP on TT4 concentrations throughout the early pregnancy may begin from the embryonic stage (gestational weeks 5 to 8).

Comparison of Recruitment Strategy Outcomes in the National Children's Study

BACKGROUND AND OBJECTIVES

In 2000, the US Congress authorized the National Institutes of Health to conduct a prospective national longitudinal study of environmental influences on children's health and development from birth through 21 years. Several recruitment methodologies were piloted to determine the optimal strategy for a main National Children's Study.

METHODS

After an initial pilot recruitment that used a household enumeration strategy performed poorly, the National Children's Study Vanguard Study developed and evaluated the feasibility, acceptability, and cost of 4 alternate strategies to recruit a large prospective national probability sample of pregnant women and their newborn children. We compare household-based recruitment, provider-based recruitment, direct outreach, and provider-based sampling (PBS) strategies with respect to overall recruitment success, efficiency, cost, and fulfillment of scientific requirements.

RESULTS

Although all 5 strategies achieved similar enrollment rates (63%-81%) among eligible women, PBS achieved the highest recruitment success as measured by the ratio of observed-to-expected newborn enrollees per year of 0.99, exceeding those of the other strategies (range: 0.35-0.48). Because PBS could reach the enrollment target through sampling of high volume obstetric provider offices and birth hospitals, it achieved the lowest ratio of women screened to women enrolled and was also the least costly strategy. With the exception of direct outreach, all strategies enrolled a cohort of women whose demographics were similar to county natality data.

CONCLUSIONS

PBS demonstrated the optimal combination of recruitment success, efficiency, cost, and population representativeness and serves as a model for the assembly of future prospective probability-based birth cohorts.

Maternal serum lead level during pregnancy is positively correlated with risk of preterm birth in a Chinese population

Lead (Pb) is a well-known developmental toxicant. The aim of the present study was to analyze the association between maternal serum Pb level and risk of preterm birth in a population-based birth cohort study. The present study analyzed a sub-study of the China-Anhui Birth Cohort that recruited 3125 eligible mother-and-singleton-offspring pairs. Maternal serum Pb level was measured by graphite furnace atomic absorption spectrometry. All subjects were classified into three groups by tertile division according to serum Pb level: Low-Pb (L-Pb, <1.18 μg/dl), Medium-Pb (M-Pb, 1.18-1.70 μg/dl), and High-Pb (H-Pb, ≥1.71 μg/dl). The rate of preterm birth was 2.8% among subjects with L-Pb, 6.1% among subjects with M-Pb, and 8.1% among subjects with H-Pb, respectively. After controlling confounding factors, the adjusted OR for preterm birth was 2.33 (95%CI: 1.49, 3.65) among subjects with M-Pb and 3.09 (95%CI: 2.01, 4.76) among subjects with H-Pb. Of interest, maternal Pb exposure in early gestational stage than in middle gestational stage was more susceptible to preterm birth. Moreover, maternal serum Pb level was only associated with increased risk of late preterm birth. The present study provides evidence that maternal serum Pb level during pregnancy is positively associated with risk of preterm birth in a Chinese population.

Maternal depression attenuates newborn vitamin D concentrations in winter-spring: a prospective population-based study

We aimed to investigate whether the newborns of mothers with maternal depression (MD) had lower vitamin D levels than newborns of non-MD (NMD) mothers and identify the potential mechanism underlying this association. Maternal depressive symptoms in late pregnancy and concentrations of cord blood 25 hydroxyvitamin D (25(OH)D) were measured in 1491 mother-infant pairs. Data on maternal sociodemographic characteristics, health status, lifestyle and birth outcomes were prospectively collected. For infants born in winter-spring, the infants of MD mothers had significantly reduced concentrations of 25(OH) D (adjusted β = −3.51 nmol/L; 95% CI: −6.19, −0.84; P = 0.010) and lower birth weight (3267 ± 470 g vs 3348 ± 598 g, F = 4.64, P = 0.031), compared with the infants of NMD mothers. A significant, inverse linear relationship was noted between maternal depression scores and the concentration of 25(OH)D for infants born in winter-spring (adjusted β = −0.158; 95% CI: −0.259, −0.057). The significant, inverse linear relationship between maternal depression scores and fetomaternal ratios of 25(OH) D was also observed among the infants born in winter-spring (adjusted β = −0.005; 95% CI: −0.008, −0.003). MD appears to significantly attenuate the vitamin D concentrations and birth weight of infants born in winter-spring. A decreased fetomaternal ratio of 25(OH)D might be involved in this biological pathway.

The Born in Guangzhou Cohort Study (BIGCS)

The Born in Guangzhou Cohort Study (BIGCS) is a large-scale prospective observational study investigating the role of social, biological and environmental influences on pregnancy and child health and development in an urban setting in southern China. Pregnant women who reside in Guangzhou and who attend Guangzhou Women and Children's Medical Center (GWCMC) for antenatal care in early pregnancy (<20 weeks' gestation) are eligible for inclusion. Study recruitment commenced in February 2012, with an overall participation rate of 76.3%. Study recruitment will continue until December 2018 to achieve the target sample size of 30,000 mother-child pairs. At 30 April 2016, a total of 75,422 questionnaires have been collected, while 14,696 live births have occurred with planned follow-up of cohort children until age 18 years. During the same period a total of 1,053,000 biological samples have been collected from participants, including maternal, paternal and infant blood, cord blood, placenta, umbilical cord, and maternal and infant stool samples. The dataset has been enhanced by record linkage to routine health and administrative records. We plan future record linkage to school enrolment and national examination records.

Prenatal exposure to famine and the development of hyperglycemia and type 2 diabetes in adulthood across consecutive generations: a population-based cohort study of families in Suihua, China

BACKGROUND

There has been increased recognition that prenatal or perinatal nutrition has an effect on the development of type 2 diabetes (T2D) in adulthood, although studies that have directly examined whether the effect could be transmitted to the next generation remain sparse.

OBJECTIVE

We investigated the role of prenatal exposure to the Chinese famine in affecting future T2D risk in adulthood in 2 consecutive generations.

DESIGN

A total of 1034 families, including 2068 parents [parental generation (F1)] and 1183 offspring [offspring generation (F2)], were recruited from the Suihua rural area that was affected by the Chinese Famine of 1959-1961. Participants born between 1 October 1959 and 30 September 1961 were defined as famine exposed, and those born between 1 October 1962 and 30 September 1964 were defined as nonexposed. The F2 were classified as having 1) no parent exposed to famine, 2) only a mother exposed to famine, 3) only a father exposed to famine, or 4) both parents exposed to famine. Classical risk factors for T2D as well as fasting-glucose- and oral-glucose-tolerance tests were measured in both the F1 and F2.

RESULTS

Prenatal exposure to famine was associated with elevated risks of hyperglycemia (multivariable-adjusted OR: 1.93; 95% CI: 1.51, 2.48) and T2D (OR: 1.75; 95% CI: 1.20, 2.54) in adulthood in F1. Furthermore, compared with the offspring of nonexposed parents, the F2 with exposed parents- especially both exposed parents-had increased hyperglycemia risk (OR: 2.02; 95% CI: 1.12, 3.66) in adulthood.

CONCLUSION

Prenatal exposure to famine remarkably increases hyperglycemia risk in 2 consecutive generations of Chinese adults independent of known T2D risk factors, which supports the notion that prenatal nutrition plays an important role in the development of T2D across consecutive generations of Chinese adults. This trial was registered at www.chictr.org.cn as ChiCTR-ECH-13003644.

Association of maternal serum cadmium level during pregnancy with risk of preterm birth in a Chinese population

Cadmium (Cd) was a developmental toxicant that induces fetal malformation and growth restriction in mice. However, epidemiological studies about the association of maternal serum Cd level with risk of preterm birth were limited. This study was to investigate whether maternal serum Cd level during pregnancy is associated with risk of preterm birth in a Chinese population. Total 3254 eligible mother-and-singleton-offspring pairs were recruited. Maternal serum Cd level was measured by GFAAS. Based on tertiles, maternal serum Cd concentration was classified as low (LCd, <0.65 μg/L), medium (MCd, 0.65-0.94 μg/L) and high (HCd, ≥0.95 μg/L). Odds ratio (OR) for preterm birth was estimated using multiple logistic regression models. Results showed the rate of preterm birth among LCd, M-Cd and HCd was 3.5%, 3.8%, and 9.4%, respectively. Subjects with HCd had a significantly higher risk for preterm birth (OR: 2.86; 95%CI: 1.95, 4.19; P < 0.001) than did those with LCd. Adjusted OR for preterm birth was 3.02 (95%CI: 2.02, 4.50; P < 0.001) among subjects with HCd compared to subjects with LCd. Taken together, the above results suggest that maternal serum Cd level during pregnancy is positively associated with risk of preterm birth.

Hormone concentrations throughout uncomplicated pregnancies: a longitudinal study

Background

Evidence suggests that the hormonal milieu of pregnancy is an important determinant of subsequent cancer and other chronic diseases in both the mother and the offspring. Many of the existing maternity and birth cohorts include specimens drawn only once during pregnancy. How well a single blood specimen collected during a pregnancy characterizes exposure to these hormones throughout gestation, and also in subsequent pregnancies, is not well understood.

Methods

We used serial serum samples from 71 pregnant women (25 primiparous, 25 multiparous, and 21 with two consecutive pregnancies) with natural, complication-free pregnancies and a healthy offspring at term who participated in a population-based screening trial for congenital infections in Finland between January 1st, 1988 and June 30, 1989 and provided a blood sample in each trimester.

Results

Hormone levels were more strongly correlated between consecutive trimesters of a pregnancy than between the 1st and 3rd trimester (e.g., estradiol, r_{T1 vs. T2} = 0.51 and r_{T2 vs. T3} = 0.60, p < 0.01; r_{T1 vs. T3} = 0.32, p < 0.05). Concentrations of sRANKL remained stable throughout gestation, whereas estradiol, estrone, progesterone, testosterone, prolactin, and osteoprotegerin increased throughout pregnancy. First trimester hormone concentrations explained less of the variation in the third trimester on their own than second trimester hormone levels (e.g. estradiol R²_T1  = 16 % and R²_T2 = 42 %). Addition of maternal (e.g., smoking) and/or child characteristics (e.g., sex) improved the accuracy of the 3rd trimester estimates for some of the hormones.

Conclusions

One hormone measurement in early pregnancy, in conjunction with maternal and fetal characteristics, permits estimation of 3rd trimester hormone concentrations. Therefore, single hormone measurements available from maternity cohorts are suitable to quantify hormone exposure during pregnancy. To our knowledge, we provide the first data on correlations between hormone concentrations both across trimesters of a single pregnancy, as well as between two subsequent pregnancies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-0937-5) contains supplementary material, which is available to authorized users.

Maternal serum cadmium level during pregnancy and its association with small for gestational age infants: a population-based birth cohort study

The association between maternal cadmium (Cd) exposure during pregnancy and the increased risk of fetal growth restriction (FGR) remains controversial. The present study evaluated the association between maternal serum Cd level and risk of small for gestational age (SGA) infants in a Chinese population. The present study analyzed a subsample of the C-ABCS cohort that recruited 3254 eligible mother-and-singleton-offspring pairs. Maternal serum Cd level during pregnancy was measured by graphite furnace atomic absorption spectrometry. The rate and odds ratio (OR) for SGA infant were calculated. The rate for SGA infant was 10.6% among subjects with H-Cd (≥1.06 μg/L), significantly higher than 7.5% among subjects with L-Cd (<1.06 μg/L). OR was 1.45 (95% CI: 1.11, 1.90; P = 0.007) among subjects with H-Cd. Adjusted OR for SGA infants was 1.43 (95% CI: 1.09, 1.88; P = 0.007) among subjects with H-Cd. Taken together, we observe the fact that maternal Cd exposure at middle gestational stage, elevates the risk of SGA in contrast to early gestational stage. The present results might be interesting and worth more discussing, and guarantee to further studies.

Maternal Serum Zinc Concentration during Pregnancy Is Inversely Associated with Risk of Preterm Birth in a Chinese Population

BACKGROUND

Evidence exists that maternal zinc status during pregnancy is linked to adverse pregnancy outcomes including abortion, fetal growth restriction, and neural tube defects. However, it remains unclear whether maternal serum zinc concentration (SZC) during pregnancy is associated with risk of preterm birth.

OBJECTIVE

This study was designed to investigate the association between maternal SZC during pregnancy and risk of preterm birth.

METHODS

For this substudy of the China-Anhui Birth Cohort Study, 3081 maternal-singleton pairs with detailed birth records and available serum samples were identified. The maternal SZC was determined with flame atomic absorption spectroscopy. A total of 169 preterm births were identified. In this study, the women were divided into tertiles on the basis of their SZC: low (<76.7 μg/dL), medium (76.7-99.6 μg/dL), and high (≥99.7 μg/dL). The ORs for preterm birth were estimated by using multiple logistic regression models.

RESULTS

The median SZC was 87.3 μg/dL (range: 11.1-211 μg/dL). Incidences of preterm birth were 7.3% and 6.0% among subjects with low and medium SZCs, respectively, which were significantly higher than 3.1% among subjects with a high SZC [ORs (95% CIs) for low and medium SZCs: 2.45 (1.60, 3.74), P < 0.001, and 2.00 (1.29, 3.09), P < 0.01, respectively]. After adjustment for prepregnancy body mass index, maternal age, time of serum collection, gravidity, parity, and monthly income, adjusted ORs were 2.41 (95% CI: 1.57, 3.70; P < 0.001) and 1.97 (95% CI: 1.27, 3.05; P < 0.01) among subjects with low and medium maternal SZCs.

CONCLUSIONS

Maternal serum zinc concentration during pregnancy is inversely associated with risk of preterm birth in the Chinese population, and the results are driven by maternal SZC in the first trimester.

Maternal pre-pregnancy BMI and adverse pregnancy outcomes among Chinese women: Results from the C-ABCS

The aim of this study was to investigate associations between pre-pregnancy body mass index (BMI) and adverse pregnancy outcomes among Chinese pregnant women. A prospective population-based cohort study was performed using data collected as part of the China-Anhui Birth Cohort Study or C-ABCS. A total of 13,121 pregnant women who received the first prenatal visit were enrolled from November 2008 to October 2010. Logistic regression analysis was used to calculate associations between pre-pregnancy BMI and pregnancy outcomes. Results indicated that the increased pre-pregnancy BMI was associated with a number of adverse pregnancy outcomes such as hypertensive disorder (adjusted relative risk (ARR) 2.3, 95% confidence interval [CI] 1.5-3.6), gestational diabetes (ARR 3.5, 95% CI 2.3-5.2), caesarean delivery (ARR 2.0, 95% CI 1.6-2.4), and medically indicated preterm delivery (ARR 1.8, 95% CI 1.1-2.9). Women with pre-pregnancy BMI above the normal range pose an increased risk of adverse pregnancy outcomes.

Cord Blood 25-hydroxyvitamin D and Fetal Growth in the China-Anhui Birth Cohort Study

We determined the association of cord blood 25-hydroxyvitamin D [25(OH)D] with birth weight and the risk of small for gestational age (SGA). As part of the China-Anhui Birth Cohort (C-ABC) study, we measured cord blood levels of 25(OH)D in 1491 neonates in Hefei, China. The data on maternal sociodemographic characteristics, health status, lifestyle, birth outcomes were prospectively collected. Multiple regression models were used to estimate the association of 25(OH)D levels with birth weight and the risk of SGA. Compared with neonates in the lowest decile of cord blood 25(OH)D levels, neonates in four deciles (the fourth, fifth, sixth and seventh deciles) had significantly increased birth weight and decreased risk of SGA. Multiple linear regression models showed that per 10 nmol/L increase in cord blood 25(OH)D, birth weight increased by 61.0 g (95% CI: 31.9, 89.9) at concentrations less than 40 nmol/L, and then decreased by 68.5 g (95% CI: -110.5, -26.6) at concentrations from 40 to 70 nmol/L. This study provides the first epidemiological evidence that there was an inverted U shaped relationship between neonatal vitamin D status and fetal growth, and the risk of SGA reduced at moderate concentration.

Maternal zinc deficiency during pregnancy elevates the risks of fetal growth restriction: a population-based birth cohort study

We investigated the association between maternal zinc level during pregnancy and the risks of low birth weight (LBW) and small for gestational age (SGA) infants in a large population-based birth cohort study. In this study, 3187 pregnant women were recruited. For serum zinc level, 2940 pregnant women were sufficient (≥56 μg/dL) and 247 deficient (<56 μg/dL). Of interest, 7.3% newborns were with LBW among subjects with low zinc level (RR: 3.48; 95% CI: 2.03, 5.96; P < 0.001). Adjusted RR for LBW was 3.41 (95% CI: 1.97, 5.91; P < 0.001) among subjects with low zinc level. Moreover, 15.0% newborns were with SGA among subjects with low zinc level (RR: 1.98; 95% CI: 1.36, 2.88; P < 0.001). Adjusted RR for SGA was 1.93 (95% CI: 1.32, 2.82; P < 0.001) among subjects with low zinc level. A nested case-control study within above cohort showed that maternal serum zinc level was lower in SGA cases as compared with controls. By contrast, maternal serum C-reactive protein, TNF-α and IL-8 levels were significantly higher in SGA cases than that of controls. Moreover, nuclear NF-κB p65 was significantly up-regulated in placentas of SGA cases as compared with controls. Taken together, maternal zinc deficiency during pregnancy elevates the risks of LBW and SGA infants.

Cord blood vitamin D and neurocognitive development are nonlinearly related in toddlers

BACKGROUND

Little is known about the relation between vitamin D status in early life and neurodevelopment outcomes.

OBJECTIVE

This study was designed to examine the association of cord blood 25-hydroxyvitamin D [25(OH)D] at birth with neurocognitive development in toddlers.

METHODS

As part of the China-Anhui Birth Cohort Study, 363 mother-infant pairs with complete data were selected. Concentrations of 25(OH)D in cord blood were measured by radioimmunoassay. Mental development index (MDI) and psychomotor development index (PDI) in toddlers were assessed at age 16-18 mo by using the Bayley Scales of Infant Development. The data on maternal sociodemographic characteristics and other confounding factors were also prospectively collected.

RESULTS

Toddlers in the lowest quintile of cord blood 25(OH)D exhibited a deficit of 7.60 (95% CI: -12.4, -2.82; P = 0.002) and 8.04 (95% CI: -12.9, -3.11; P = 0.001) points in the MDI and PDI scores, respectively, compared with the reference category. Unexpectedly, toddlers in the highest quintile of cord blood 25(OH)D also had a significant deficit of 12.3 (95% CI: -17.9, -6.67; P < 0.001) points in PDI scores compared with the reference category.

CONCLUSIONS

This prospective study suggested that there was an inverted-U-shaped relation between neonatal vitamin D status and neurocognitive development in toddlers. Additional studies on the optimal 25(OH)D concentrations in early life are needed.

Epigenetic change as the major mediator of fetal programming in humans: Are we there yet?

The developmental origins of health and disease (DOHaD) hypothesis predicts that environmental exposures experienced early in life have the potential to modify the risk associated with later-onset disease. The DOHaD hypothesis is supported by a large number of direct animal studies and a smaller number of compelling observational studies in humans, but the mechanism(s) underlying the 'programming' effects of DOHaD remain largely unclear. Given the inherent property of environmental sensitivity, the demonstrated role in gene regulation, and the capacity for stable maintenance over time once established, epigenetic variation has rapidly emerged as a candidate mediator of such effects. However, little direct evidence exists in humans, primarily due to the inherent problems associated with unraveling the relative contributions of genetic and environmental influences to phenotypic outcomes. Robust evidence is required in several domains to establish epigenetic variation in the causal pathway to DoHAD-associated disease. Firstly, interindividual epigenetic variability in response to specific early-life environmental exposures needs to be demonstrated. Further, compelling data linking specific epigenetic variants to specific disease(s) is needed. Epigenetic variation should be apparent in a tissue relevant to the disease of interest prior to phenotypic onset in order to avoid confounding and the potential for reverse causation. Finally, the functional relevance of specific epigenetic change must be demonstrated. Compelling evidence is mounting in each of these domains but remains somewhat fragmented, providing small pieces of the overall complex puzzle. It is likely that only large longitudinal life course studies commencing prior to birth, with extensive environmental exposure data and biospecimens, can provide direct evidence in support of a role of epigenetic processes as drivers of the DOHaD in humans.

Rationale and design of the PRegnancy and Infant DEvelopment (PRIDE) Study

BACKGROUND

To optimise the health of pregnant women and their children by evidence-based primary and secondary prevention, more scientific knowledge is needed. To overcome the methodological limitations of many studies on pregnancy and child health, which often use a retrospective design, we established the PRIDE (PRegnancy and Infant DEvelopment) Study.

METHODS AND RESULTS

The PRIDE Study is a large prospective cohort study that aims at including 150 000-200 000 women in early pregnancy to study a broad range of research questions pertaining to pregnancy complications, maternal and child health, and adverse developmental effects in offspring. Women are invited to participate by their prenatal care provider before or at their first prenatal care visit and are asked to fill out web-based questionnaires in gestational weeks 8-10, 17, and 34, as well as biannually throughout childhood. In addition, a food frequency questionnaire and a paternal questionnaire are administered and medical records are consulted. Multiple validation studies will be conducted and paper-and-pencil questionnaires are available for women who cannot or do not want to participate through the Internet. For subgroups of participants, blood and saliva samples for genetic and biochemical analyses are being collected. The pilot phase, which started in July 2011, showed a response rate of 47%. Recruitment will eventually cover all of the Netherlands.

CONCLUSIONS

We expect that this study, which will be the largest birth cohort in the world so far, will provide new insights in the aetiology of disorders and diseases that originate in pregnancy. The PRIDE Study is open for collaboration.