Maternal Smoking, Breastfeeding, and Risk of Childhood Overweight: Findings from a National Cohort

To examine the association between exposure to tobacco compounds in breast milk and risk of childhood overweight, we used historical data for a subset of 21,063 mother–child pairs in the US Collaborative Perinatal Project. Based on self-reports, mothers were classified as non-smokers, light (1–9 cigarettes/day), moderate (10–19), or heavy (20+) smokers. Feeding type (exclusive breastfeeding or bottle-feeding) was observed during nursery stay after birth. We stratified children by maternal smoking and feeding type, and then fit interaction terms to isolate exposure to tobacco compounds via breast milk from exposure in uterus and in ambient air after birth. Using measured weight and height, overweight at age 7 was defined as a body mass index ≥85th percentile by sex and age. Among exclusively bottle-fed children, adjusted odds ratios (ORs) of overweight at age 7 were 1.24 (95 % confidence interval [CI], 1.12–1.38; vs. non-smoking) for light maternal smoking, 1.43 (95 % CI, 1.25–1.63) for moderate maternal smoking, and 1.46 (95 % CI, 1.28–1.66) for heavy maternal smoking. Among exclusively breastfed children, the corresponding ORs were 1.33 (95 % CI, 0.96–1.84) for light, 1.86 (95 % CI, 1.27–2.73) for moderate, and 2.22 (95 % CI, 1.53–3.20) for heavy maternal smoking. There was a modest positive interaction between breastfeeding and heavy maternal smoking on overweight risk at age 7. Tobacco compounds via breast milk of smoking mothers (significantly for heavy smokers) appear to be associated with a modest elevation in childhood overweight risk at 7 years of age. More aggressive intervention is needed to help pregnant and breastfeeding women to quit smoking.     

Smoking,physical exercise,BMI and late foetal death: a study within the Danish National Birth Cohort

The aim of this paper was to estimate the effect of maternal and paternal smoking on foetal death (miscarriage and stillbirth) and to estimate potential interactions with physical exercise and pre-pregnancy body mass index. We selected 87,930 pregnancies from the population-based Danish National Birth Cohort. Information about lifestyle, occupational, medical and obstetric factors was obtained from a telephone interview and data on pregnancy outcomes came from the Danish population based registries. Cox regression was used to estimate the hazard ratios (adjusted for potential confounders) for predominantly late foetal death (miscarriage and stillbirth). An interaction contrast ratio was used to assess potential effect measure modification of smoking by physical exercise and body mass index. The adjusted hazard ratio of foetal death was 1.22 (95 % CI 1.02–1.46) for couples where both parents smoked compared to non-smoking parents (miscarriage: 1.18, 95 % CI 0.96–1.44; stillbirth: 1.32, 95 % CI 0.93–1.89). On the additive scale, we detected a small positive interaction for stillbirth between smoking and body mass index (overweight women). In conclusion, smoking during pregnancy was associated with a slightly higher hazard ratio for foetal death if both parents smoked. This study suggests that smoking may increase the negative effect of a high BMI on foetal death, but results were not statistically significant for the interaction between smoking and physical exercise.     

妊娠期被动吸烟与出生缺陷关系的Meta分析

目的探讨孕期被动吸烟与出生缺陷的关系。方法运用计算机检索1980年至2010年4月国内外关于孕期被动吸烟与出生缺陷关系的研究文献,采用Cochrane协作网提供的RevMan5.0分析软件对入选的文献进行异质性检验,经Meta分析计算合并效应OR值及其95%CI。结果国内外25篇文献入选。森林图显示纳入文献是异质的(χ2=243.98,P0.000 01),采用随机效应模型计算孕期被动吸烟与出生缺陷关联性的合并效应的OR值为1.70,95%CI:1.34~2.15。其中,国内和国外不同研究人群合并效应的OR值分别为3.62(95%CI:1.71~7.68)和1.28(95%CI:1.04~1.57)。结论孕期被动吸烟可能会增加出生缺陷发生风险。     

中国国家出生队列建设背景和设计简介

随着生活行为方式、自然和社会环境的急剧变化,育龄人口生殖健康状况持续下降,快速增加的由辅助生殖技术（ART）孕育的子代的远期健康状况亟待评估。因此,妇幼保健和生殖健康相关研究关注的重点亟需从妊娠期、围产期的死亡和严重疾病表型逐渐向全生命周期和全疾病谱拓展。为了满足这样的研究需求,在我国12个省（自治区、直辖市）启动了中...     

Maternal use of nicotine replacement therapy during pregnancy and offspring birthweight: a study within the Danish National Birth Cohort

Lassen TH, Madsen M, Skovgaard LT, Strandberg‐Larsen K, Olsen J, Andersen A‐MN. Maternal use of nicotine replacement therapy during pregnancy and offspring birthweight: a study within the Danish National Birth Cohort. Paediatric and Perinatal Epidemiology 2010; 24: 272–281. Smoking is a well‐established risk factor for fetal growth restriction and other adverse pregnancy outcomes, and nicotine may be one of the chemical compounds that drive these associations. Nicotine replacement therapy (NRT) is a smoking cessation aid, which can facilitate smoking cessation. It is, however, unknown whether NRT used during pregnancy impairs fetal growth. The aim of this study was to estimate the association between the use of NRT during pregnancy and offspring birthweight. The study population consisted of 72 761 women enrolled in the Danish National Birth Cohort between 1996 and 2002. Information on NRT and potential confounders was obtained from two computer‐assisted telephone interviews conducted in the second and third trimesters, respectively. Multiple linear regression in a multilevel model was used to estimate the association between NRT use and birthweight adjusted for gestational age and potential confounders. The adjusted analyses showed no significant association between the duration of NRT use and birthweight (b = 0.25 g per week of NRT use [95% CI ?2.31, 2.81]) and neither was the type of NRT product (patch, gum, inhaler) associated with reduced birthweight. However, simultaneous use of more than one NRT product was associated with reduced birthweight (b = ?10.73 g per week of NRT use [95% CI ?26.51, 5.05]), although the association was not statistically significant. The results of this study suggest that maternal use of NRT in pregnancy does not seriously affect birthweight, but there could be a negative effect on birthweight associated with simultaneous use of more than one type of NRT product.     

Maternal stress during pregnancy and gestational duration: A cohort study from the Danish National Birth Cohort

Background

Preterm birth is one of the most important contributors to neonatal mortality and morbidity. Experiencing stress during pregnancy may increase the risk of adverse birth outcomes, including preterm birth. This association has been observed in previous studies, but differences in measures used limit comparability.

Objective

The objective of the study was to investigate the association between two measures of maternal stress during pregnancy, life stress and emotional distress, and gestation duration.

Methods

Women recruited in the Danish National Birth Cohort from 1996 to 2002, who provided information on their stress level during pregnancy and expecting a singleton baby, were included in the study. We assessed the associations between the level of life stress and emotional distress in quartiles, both collected at 31 weeks of pregnancy on average, and the rate of giving birth using Cox regression within intervals of the gestational period.

Results

A total of 80,991 pregnancies were included. Women reporting moderate or high levels of life stress vs no stress had a higher rate of giving birth earlier within all intervals of gestational age (e.g. high level: 27–33 weeks: hazard ratio (HR) 1.38, 95% confidence interval (CI) 1.04, 1.84; 34–36 weeks: 1.10, 95% CI 0.97, 1.25; 37–38 weeks: 1.21, 95% CI 1.15, 1.28). These associations between life stress and preterm birth were mainly driven by pregnancy worries. For emotional distress, a high level of distress was associated with shorter length of gestation in the preterm (27–33 weeks: 1.38, 95% CI 1.02, 1.86; 34–36 weeks: 1.05, 95% CI 0.91, 1.19) and early term (1.11, 95% CI 1.04, 1.17) intervals.

Conclusions

Emotional distress and life stress were shown to be associated with gestational age at birth, with pregnancy-related stress being the single stressor driving the association. This suggests that reverse causality may, at least in parts, explain the earlier findings of stress as a risk factor for preterm birth.     

中国国家出生队列研究的理念与实践

出生队列研究在探讨生命早期暴露对子代远期健康的影响中发挥重要作用。随着育龄人口生殖健康问题的凸显, 辅助生殖技术被广泛应用于临床。而关于辅助生殖技术对母婴健康的远期影响尚未得到充分研究。2016年, 以家庭为单位, 同步招募辅助受孕家庭和自然受孕家庭的多中心前瞻性的中国国家出生队列(CNBC)研究正式启动。截至2021年6月30日, 已累计在全国招募7.2万个家庭, 包括辅助生殖家庭3.9万个和自然妊娠家庭3.3万个, 本队列以面对面随访的形式在辅助生殖治疗前、胚胎移植、孕早期、孕中期、孕晚期及分娩时以及婴儿出生后42 d、6个月、1岁、3岁时采集数据信息和生物样本。其主要目标为评估使用辅助生殖技术后诞生子代的发育和健康状况, 发现与不良出生结局和儿童期疾病相关的危险因素, 为提升出生人口质量的策略制定提供科学依据。本文将对国家出生队列的建设概况和研究进展做简要介绍。     

Associations between Maternal Dietary Patterns and Infant Birth Weight in the NISAMI Cohort: A Structural Equation Modeling Analysis

The mother’s diet during pregnancy is associated with maternal and child health. However, there are few studies with moderation analysis on maternal dietary patterns and infant birth weight. We aim to analyse the association between dietary patterns during pregnancy and birth weight. A prospective cohort study was performed with pregnant women registered with the prenatal service (Bahia, Brazil). A food frequency questionnaire was used to evaluate dietary intake. Birth weight was measured by a prenatal service team. Statistical analyses were performed using factor analysis with a principal component extraction technique and structural equation modelling. The mean age of the pregnant women was 27 years old (SD: 5.5) and the mean birth weight was 3341.18 g. It was observed that alcohol consumption (p = 0.05) and weight-gain during pregnancy (p = 0.05) were associated with birth weight. Four patterns of dietary consumption were identified for each trimester of the pregnancy evaluated. Adherence to the “Meat, Eggs, Fried Snacks and Processed foods” dietary pattern (pattern 1) and the “Sugars and Sweets” dietary pattern (pattern 4) in the third trimester directly reduced birth weight, by 98.42 g (Confidence interval (CI) 95%: 24.26, 172.59) and 92.03 g (CI 95%: 39.88, 165.30), respectively. It was also observed that insufficient dietary consumption in the third trimester increases maternal complications during pregnancy, indirectly reducing birth weight by 145 g (CI 95%: −21.39, −211.45). Inadequate dietary intake in the third trimester appears to have negative results on birth weight, directly and indirectly, but more studies are needed to clarify these causal paths, especially investigations of the influence of the maternal dietary pattern on the infant gut microbiota and the impacts on perinatal outcomes.     

Folic Acid Supplementation and the Association between Maternal Airborne Particulate Matter Exposure and Preterm Delivery: A National Birth Cohort Study in China

Background: Potential modification of the association between maternal particulate matter (PM) exposure and preterm delivery (PTD) by folic acid (FA) supplementation has not been studied.Objective: We examined whether FA supplementation could reduce the risk of PTD associated with maternal exposure to PM in ambient air during pregnancy.Method: In a cohort study covering 30 of the 31 provinces of mainland China in 2014, 1,229,556 primiparas of Han ethnicity were followed until labor. We collected information on their FA supplementation and pregnancy outcomes and estimated each participant’s exposure to PM with diameters of ≤10μm (PM10), 2.5μm (PM2.5), and 1μm (PM1) using satellite remote-sensing based models. Cox proportional hazard regression models were used to examine interactions between FA supplementation and PM exposures, after controlling for individual characteristics.Results: Participants who initiated FA ≥3 months prior to pregnancy (38.1%) had a 23% [hazard ratio (HR)=0.77 (95% CI: 0.76, 0.78)] lower risk of PTD than women who did not use preconception FA. Participants with PM concentrations in the highest quartile had a higher risk of PTD [HR=1.29 (95% CI: 1.26, 1.32) for PM1, 1.52 (95% CI: 1.46, 1.58) for PM2.5, and 1.22 (95% CI: 1.17, 1.27) for PM10] than those with exposures in the lowest PM quartiles. Estimated associations with a 10-μg/m3 increase in PM1 and PM2.5 were significantly lower among women who initiated FA ≥3 months prior to pregnancy [HR=1.09 (95% CI: 1.08, 1.10) for both exposures] than among women who did not use preconception FA [HR=1.12 (95% CI: 1.11, 1.13) for both exposures; pinteraction<0.001]. The corresponding association was also significantly lower for a 10-μg/m3 increase in PM10 [HR=1.03 (95% CI: 1.02, 1.03) for FA ≥3 months before pregnancy vs. 1.04 (95% CI: 1.03, 1.04) for no preconception FA; pinteraction<0.001].Conclusion: Our findings require confirmation in other populations, but they suggest that initiating FA supplementation ≥3 months prior to pregnancy may lessen the risk of PTD associated with PM exposure during pregnancy among primiparas of Han ethnicity. https://doi.org/10.1289/EHP6386     

Birth Weight,Maternal Body Mass Index,and Early Childhood Growth: A Prospective Birth Cohort Study in China

Background

The relations of birth weight and maternal body mass index (BMI) to overweight remain unresolved. We prospectively examined the relations of birth weight with various anthropometric measures at age 3 to 6 years, the effect of maternal BMI, and the patterns of these relations in an analysis using 9 birth weight categories.

Methods

The subjects were 210 172 singleton infants born alive with a gestational age ≥28 weeks between October 1993 and December 1996; the subjects were followed up in 2000. Birth weight, maternal height and weight, and other relevant information were measured or collected prospectively. Overweight and underweight were defined by using National Center for Health Statistics/World Health Organization reference data. Logistic regression models were used to estimate relative risks. Analyses stratified by quartile of maternal BMI were performed to examine the effects of maternal BMI on the associations of birth weight with overweight and underweight.

Results

Birth weight was linearly associated with height, weight, and BMI at age 3–6 years. Adjustment for maternal BMI did not alter this association. Birth weight was positively associated with overweight and negatively associated with underweight. The relation curves for both overweight and underweight resembled half of a flat parabolic curve. The associations for overweight and underweight were slightly stronger for the highest and lowest quartiles of maternal BMI, respectively.

Conclusions

Higher birth weight is associated with an increased risk for childhood overweight, and lower birth weight with an increased risk for underweight. The associations between birth weight and early childhood anthropometric growth measures could not explained by maternal BMI.Key words: birth weight, overweight, underweight, maternal body mass index     

中国国家出生队列研究质量控制策略与措施

出生队列是研究孕前和孕期各种环境暴露因素与胎儿、婴幼儿、青少年健康之间关系的有效方法。出生队列建设周期长、环节众多,研究质量可能受到多种因素的影响。本文对中国国家出生队列建设过程中的各项质量保证和质量控制措施进行梳理,归纳总结建设经验。以期为相关队列研究提供经验,减少相关因素对队列研究的影响,提升队列研究质量。中国国家出生队列在质量保证的顶层设计方面采取一系列措施保障研究质量,包括研究中心筛选、成员管理系统开发、标准化操作流程制定及工作人员规范化培训;在质量控制方面,包括针对队列数据产生过程的实时、及时、定时质控,针对生物样本采集、处理及保存的全周期质控,以及针对参与工作人员的培训、督查和量化考核的全面立体质控。     

Hospital Work and Pregnancy Outcomes: A Study in the Danish National Birth Cohort

Abstract

In hospitals, women of reproductive age do a range of work tasks, some of which are known to carry potential risks. Tasks such as working with radiation, chemicals, and infectious agents, as well as performing heavy lifting or tasks requiring erratic sleep patterns have been reported to increase the risk of reproductive failures. Our aim was to study pregnancy outcomes in female hospital workers in Denmark. We performed a cohort study of 5976 female hospital workers and used as a reference group 60,890 women employed outside of hospitals. The reproductive health of hospital workers working during pregnancy is comparable to those of non-hospital workers for the majority of reproductive failures studied. However, an increased prevalence of congenital abnormalities was noted in some subgroups of hospital workers, which may indicate that some hospital work still entails fetotoxic hazards.     

Perfluorinated chemicals and fetal growth: a study within the Danish National Birth Cohort

Background

Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are man-made, persistent organic pollutants widely spread throughout the environment and human populations. They have been found to interfere with fetal growth in some animal models, but whether a similar effect is seen in humans is uncertain.

Objectives

We investigated the association between plasma levels of PFOS and PFOA in pregnant women and their infants’ birth weight and length of gestation.

Methods

We randomly selected 1,400 women and their infants from the Danish National Birth Cohort among those who completed all four computer-assisted telephone interviews, provided the first blood samples between gestational weeks 4 and 14, and who gave birth to a single live-born child without congenital malformation. PFOS and PFOA were measured by high performance liquid chromatography–tandem mass spectrometer.

Results

PFOS and PFOA levels in maternal plasma were on average 35.3 and 5.6 ng/mL, respectively. Only PFOA levels were inversely associated with birth weight (adjusted β = −10.63 g; 95% confidence interval, −20.79 to −0.47 g). Neither maternal PFOS nor PFOA levels were consistently associated with the risk for preterm birth or low birth weight. We observed no adverse effects for maternal PFOS or PFOA levels on small for gestational age.

Conclusion

Our nationwide cohort data suggest an inverse association between maternal plasma PFOA levels and birth weight. Because of widespread exposure to these chemicals, our findings may be of potential public health concern.     

A Longitudinal Analysis of Adolescent Smoking and its Correlates

ABSTRACT: When designing effective programs, it is important to identify factors associated with tobacco use at particular stages of adolescence, as well as factors associated with changes in tobacco use. This study examined cross-sectional correlates of smoking during early adolescence and during late adolescence in a longitudinal sample to compare the pattern of prediction of smoking at both stages. Changes in predictor variables related to changes in smoking also were examined. Results showed intentions to smoke was the strongest predictor of smoking during both early adolescence and during late adolescence; however, it was a much stronger predictor for the late adolescent stage. In addition, intentions to smoke was the strongest predictor of changes in smoking. However, the pattern of prediction at the two grade levels showed some differences as did predictors of changes in smoking. Implications for designing smoking prevention and cessation programs are addressed.     

Subfecundity as a correlate of preeclampsia: a study within the Danish National Birth Cohort

A long interpregnancy interval is associated with preeclampsia. If some women experiencing a long interval between births had difficulty conceiving, subfecundity and preeclampsia may share a common etiology. Therefore, the authors examined the association between subfecundity and preeclampsia. By using interview data collected during the second trimester of pregnancy (1998-2001) from women participating in the Danish National Birth Cohort, they identified 20,034 and 24,698 singleton livebirths to primiparous and multiparous women, respectively, for whom preeclampsia information was available from hospital birth records. Among women with no known hypertension, the authors estimated a higher risk of preeclampsia in those with longer times to pregnancy (TTPs), after adjustment for maternal age, prepregnancy body mass index, and smoking. Compared with primiparas who became pregnant right away (referent category), the risk of preeclampsia increased with TTP and then stabilized for women taking 6 months or longer to conceive, whose risk of preeclampsia increased by 50%. Multiparas also had an increased risk, but only those reporting a TTP longer than 12 months (odds ratio = 2.47, 95% confidence interval: 1.30, 4.69). The authors found that a long TTP was associated with preeclampsia, supporting the hypothesis that some factors delaying clinically recognized conception may also be in a causal pathway for preeclampsia.