Prenatal exposure to methylmercury and LCPUFA in relation to birth weight

BackgroundEpidemiologic studies have been inconclusive regarding the impact of coexposure to long chain polyunsaturated fatty acids (LCPUFA) and methylmercury (MeHg) from fish consumption during pregnancy on measures of fetal development.ObjectivesWe evaluated the association between birth weight and prenatal maternal LCPUFA status and MeHg exposure in the Republic of Seychelles.MethodsWe measured LCPUFA in maternal whole blood collected at 28 weeks of gestation and following delivery and MeHg in maternal hair obtained at delivery. There were 230 births with complete data on birth weight and covariates. Multiple linear regression models controlled for infant sex, gestational age, maternal age, smoking during pregnancy, intrapartum weight gain, prepregnancy body mass index, maternal socioeconomic status, parity, gestational diabetes, and alcohol use during pregnancy.ResultsThe average birth weight was 3252 g (range 1654–4450) and the average gestational age was 39 weeks (range 34–41). Prenatal MeHg exposure and maternal LCPUFA status were not associated with birth weight. Infant sex and length of gestation were the only predictors, with male sex and increased gestational age consistently associated with greater birth weight.ConclusionsThese findings do not support a relationship between prenatal exposure to LCPUFA and/or MeHg from fish consumption and birth weight.     

The effect of nutritional intake on outcome of pregnancy in smokers and non-smokers

The relationship between nutrient intake and pregnancy outcome (adjusted birth weight and gestational age) was investigated in randomly selected non-smokers (n97) and in heavy smokers (15 + cigarettes/d) (n72) booking for ante-natal care at a hospital in South London. Weighted dietary intakes (7d) were obtained at 28 and 36 weeks gestation. Birth weight was adjusted for gestational age, maternal height, parity and sex of infant. Compared with non-smokers, intakes of micronutrients and fibre were lower in smokers at both 28 and 36 weeks, and smokers reduced their intakes more in late pregnancy. The babies of smokers had a lower adjusted birth weight but there was no difference in length of gestation between smokers and non-smokers. After controlling for smoking, social class and alcohol consumption, nutrient intakes at 28 weeks were found to have no effect on adjusted birth weight. However, intakes of protein, zinc, riboflavin and thiamin at 36 weeks, and the change in intakes of these nutrients (plus iron) between 28 and 36 weeks, had independent positive effects on birth weight. Some of the effect of smoking on birth weight appeared to be mediated through differences in nutrient intakes. Smoking explained 14.3% of the variance in birth weight in this population and a further 2.4-7.2% was explained by change in nutrient intakes between 28 and 36 weeks. It is recommended that women in pregnancy do not reduce their dietary intakes in late pregnancy.     

Birth weights of black African babies of migrant and nonmigrant mothers compared with those of babies of European mothers in Portugal

PURPOSE: The study aim is to investigate differences in birth weights between babies of foreign-born black African, Portugal-born black African, and Portugal-born white mothers. METHODS: Hospital records for Amadora and Sintra from July 2001 to June 2002 were collated and 2949 Portugal-born white, 461 Portugal-born black African, and 817 foreign-born black African live singleton babies were identified. The impact of biologic and social factors (infant sex, maternal age, parity, gestational age, and maternal smoking, education, and occupational class) and mode of delivery on birth weights was assessed by using multivariable regression models. RESULTS: African mothers were more likely to be of lower socioeconomic status than white Portuguese mothers, among whom rates of smoking were two to three times greater (21% among white Portuguese mothers). Small preterm babies comprised 1.5% of white Portuguese babies, 2.3% of babies of Portugal-born African mothers, and 3.9% of babies of foreign-born African mothers (p < 0.05 compared with white Portuguese babies). Compared with white Portuguese babies, mean birth weight of term babies, adjusted for sex, among Portugal-born African mothers was -24.6 g (95% confidence interval, -70.1-20.9), and among foreign-born African mothers, was +38.8 g (95% confidence interval, 2.9-74.8). Adjustment for parity, maternal age, and gestational age decreased the significant birth weight advantage of babies of foreign-born African mothers to +2.3 g (95% confidence interval, -31.9-36.5). Among nonsmokers, after adjusting for these factors, white Portuguese babies were heavier (40 g; p < 0.05) than babies of foreign-born African mothers, but among smokers, they were lighter (163 g; p < 0.05). CONCLUSIONS: Compared with white Portuguese babies, mean birth weight of term babies of foreign-born African mothers was greater, and that of babies of Portugal-born African mothers was intermediate. These differences were related to a combination of biologic factors and smoking.     

Effects of smoking and of induced abortion on pregnancy outcome

Regression analyses of preliminary data from 8818 consecutive singleton pregnancies in a study (Medical University of Debrecen, Hungary) concerning the effects of smoking during pregnancy and of a history of induced abortion on birth weight and gestational age are presented. Both individual variables and interaction effects were assessed. It was found that smoking during pregnancy decreased birth weight in a dose-response manner. Smoking works against a favorable pregnancy outcome in 2 ways: 1) lowering birth weight for gestational age, and 2) lowering gestational age in general. Previous induced abortion is associated with a downward shift in the gestational age distribution. Little effect of abortion on birth weight appeared in the sample of total births, but when stillbirths were eliminated, a significant negative effect of abortion on birth weight was seen--an effect apparent only at early gestational ages. In both aspects of this study, the following variables were controlled: maternal age, parity, education, infant sex, gestational age, and birth weight.     

Race differences in the proportion of low birth weight attributable to maternal cigarette smoking in a low-income population

PURPOSE: To quantify race differences in the public health impact of maternal cigarette smoking on infant birth weight and to estimate the proportion of low birth weight births that could be prevented by maternal smoking cessation. DESIGN: A cohort that consisted of 77,751 mother-infant pairs was evaluated retrospectively. SETTING: Statewide study of Women, Infants and Children participants in North Carolina. SUBJECTS: African-American and non-Hispanic white women who delivered a single live infant during 1988, 1989, or 1990. MEASURES: Logistic regression estimates of the relative risk of low birth weight births for smokers were used to calculate adjusted population attributable risk percentages for smoking. Separate population attributable risk percentages were calculated for total low birth weight, moderately low birth weight, and very low birth weight, and all estimates were adjusted for prepregnancy body mass index, gestational weight gain, age, education, parity, and timing of entry into prenatal care. RESULTS: Non-Hispanic whites had a much higher prevalence of smoking and were heavier smokers than African-Americans. For both moderately low birth weight and very low birth weight, the population attributable risk percentages for smoking were twice as high for non-Hispanic whites than for African-Americans. Overall, after adjustment, 30.7% of low birth weight births among non-Hispanic whites and 14.4% of low birth weight births among African-Americans were attributable to smoking. CONCLUSIONS: Although the public health impact of maternal cigarette smoking on infant birth weight was twice as high for non-Hispanic whites as for African-Americans in this low-income population, smoking cessation by all low-income pregnant women would result in significant improvements in infant health and well-being.     

Trimester of Maternal Gestational Weight Gain and Offspring Body Weight at Birth and Age Five

To investigate associations of trimester-specific GWG with fetal birth size and BMI at age 5?years. We examined 3,015 singleton births to women without pregnancy complications from the Child Health and Development Studies prospective cohort with measured weights during pregnancy. We used multivariable regression to examine the associations between total and trimester gestational weight gain (GWG) and birth weight for gestational age and child BMI outcomes, adjusting for maternal age, race/ethnicity, education, marital status, parity, pre-pregnancy body mass index (BMI), and smoking; paternal overweight, gestational age, and infant sex. We explored differences in associations by maternal BMI and infant sex. GWG in all trimesters was significantly and independently associated with birth weight with associations stronger, though not significantly, in the second trimester. First trimester GWG was associated with child BMI outcomes (OR for child overweight?=?1.05; 95% CI?=?1.02, 1.09). Each kg of first trimester GWG was significantly associated with increased child BMI z-score in women of low (???=?0.099; 95% CI?=?0.034, 0.163) and normal (???=?0.028; 95% CI?=?0.012, 0.044), but not high pre-pregnancy BMI. GWG in all trimesters was associated with birth weight; only first trimester GWG was associated with child BMI. If replicated, this information could help specify recommendations for maternal GWG and elucidate mechanisms connecting GWG to child BMI.     

妊娠期高血压及子痫前期对妊娠及新生儿结局的影响研究

目的 探讨妊娠期高血压及子痫前期对妊娠及新生儿结局的影响,为育龄妇女孕前、孕期及产后保健提供依据,以减少不良妊娠结局的发生,并为新生儿的健康管理提供预警信息。方法 以前瞻性队列研究为基础的巢式病例对照研究,暴露组84例,其中妊娠期高血压39例、子痫前期45例,按1∶1比例分层随机选择对照组(健康孕妇),使其在分娩年龄、分娩孕周、孕前体质指数、孕次、产次五方面成组匹配,比较两组间妊娠结局及新生儿情况的差别,进一步按妊娠期高血压和子痫前期对暴露组分层与对照组比较。结果 暴露组在分娩方式、早产、宫内缺氧、低出生体重儿、转新生儿科或转院、新生儿出生体重、身长、生后1 min和5 min Apgar评分方面与对照组相比,差异均存在统计学意义(P<0.05),且子痫前期导致的不良妊娠及新生儿结局更严重。结论 妊娠期高血压及子痫前期对孕妇及新生儿造成了不良影响,应当加强育龄妇女的保健,积极预防和治疗妊娠期高血压疾病,实现优生。     

Factors associated with birth weight in Sweden: the study of men born in 1913.

STUDY OBJECTIVE: To analyse factors associated with birth weight and to evaluate the validity of obstetrical data. DESIGN: Obstetrical data were retrieved for singleton men born in 1913 and living in Gothenburg, Sweden in 1963. Information on birth weight, maternal age, marital status, parity, social class, proteinuria, gestational age, and place of birth (home or hospital) was obtained from these birth records. SETTING: Sweden. PARTICIPANTS: Fifty year old men living in Gothenburg, Sweden, in 1963. MAIN RESULTS: Obstetrical records were obtained for 524 men (65%). Place of birth, gestational age, maternal age, parity, proteinuria, and marital status were all significantly correlated to birth weight. In multivariate analyses, place of birth, gestational age, parity, and proteinuria influenced birth weight. There was a substantial difference in mean birth weight between hospital deliveries (3352 g) and home deliveries (3817 g), which could be explained only partly by sociodemographic variables. Birth weight increased with parity and gestational age in home delivered babies as well as those delivered in a hospital. CONCLUSIONS: The validity of obstetrical records from 1913 was good. The place of birth (home or hospital) is strongly associated with birth weight and may be a confounding factor in studies of the implications of birth weight for future risk of disease or death.     

Increase in Child Behavior Problems Resulting from Maternal Smoking during Pregnancy

In this article, the authors investigated the effect of maternal smoking during pregnancy on behavioral problems, which were not mediated by lower birth weight, in offspring at 3 y of age. The authors used the Child Behavior Checklist for ages 2–3 y (CBCL/2–3; Achenbach, Edelbrock and Howell) to assess behavioral problems in 1 3 77 2- to 3-y-old healthy twin pairs. Soon after the birth of twins, the authors collected pre- and perinatal information, including smoking habits of the mother during pregnancy. The question “Did you smoke during pregnancy?” could be answered by choosing one of three possible options: (1) never, (2) sometimes, or (3) regularly. The authors analyzed the effect of maternal smoking on the Child Behavioral Checklist total score and on several subscale scores for first- and second-born twins separately, and they adjusted for the possible confounding effects of birth weight, socioeconomic status, maternal age, and having been breast- or bottlefed. There was a significant effect of maternal smoking on so-called externalizing behavior problems (oppositional, aggressive, overactive), but not on internalizing behavior problems (withdrawn, depressed, anxious), in both first- and second-born twins. The authors primarily attributed the enhanced externalizing problems to increased aggression. Although boys had higher externalizing (and aggression) scores than girls, the effect of maternal smoking was the same for boys and girls. The authors also discuss whether maternal smoking causes externalizing behavior problems.     

Are gestational age,birth weight,and birth length indicators of favorable fetal growth conditions? A structural equation analysis of Filipino infants

The fetal origins hypothesis emphasizes the life‐long health impacts of prenatal conditions. Birth weight, birth length, and gestational age are indicators of the fetal environment. However, these variables often have missing data and are subject to random and systematic errors caused by delays in measurement, differences in measurement instruments, and human error. With data from the Cebu (Philippines) Longitudinal Health and Nutrition Survey, we use structural equation models, to explore random and systematic errors in these birth outcome measures, to analyze how maternal characteristics relate to birth outcomes, and to take account of missing data. We assess whether birth weight, birth length, and gestational age are influenced by a single latent variable that we call favorable fetal growth conditions (FFGC) and if so, which variable is most closely related to FFGC. We find that a model with FFGC as a latent variable fits as well as a less parsimonious model that has birth weight, birth length, and gestational age as distinct individual variables. We also demonstrate that birth weight is more reliably measured than is gestational age. FFGCs were significantly influenced by taller maternal stature, better nutritional stores indexed by maternal arm fat and muscle area during pregnancy, higher birth order, avoidance of smoking, and maternal age 20–35 years. Effects of maternal characteristics on newborn weight, length, and gestational age were largely indirect, operating through FFGC. Copyright © 2013 John Wiley & Sons, Ltd.     

Child behavior problems increased by maternal smoking during pregnancy

We investigated the effects of maternal smoking during pregnancy on behavioral problems (i.e., not mediated by low birth weight) in 3-y-old offspring. We assessed behavioral problems in 1377 2- to 3-y-old twin pairs (registered in the Netherlands Twin Register) with the Child Behavior Checklist for ages 2-3 y (CBCL/2-3) from Achenbach, Edelbrock, and Howell. Two to 3 y earlier (i.e., soon after the birth of the twins) we collected information about the smoking habits (i.e., "never," "sometimes," and "regularly") of the mother during pregnancy. We analyzed the effect of maternal smoking on the CBCL total score and on several subscale scores for first- and second-born twins separately, and we adjusted for the possible confounding effects of birth weight, socioeconomic status, maternal age, and type of feeding (i.e., breast or bottle fed). There was a significant effect of maternal smoking on so-called "externalizing" behavioral problems (e.g., oppositional, aggressive, overactive), but not on "internalizing" behavioral problems (e.g., withdrawn, depressed, anxious), in both first- and second-born twins. The enhanced "externalizing" problems were attributed predominantly to increased aggression. Although boys have higher externalizing and aggression scores than girls, the effect of maternal smoking was the same for boys and girls.     

Antecedents of macrosomia.

Antecedents of high birthweight (macrosomia) were studied using the state birth certificates of White singleton infants born in three large metropolitan counties of Washington State from 1984 to 1986. Cases consisted of 2082 live-born macrosomic infants, defined by a birthweight of over 4.5 kg. A random sample of 4440 live births with birthweights of 2.5-4.0 kg was selected as a comparison group. Estimates for the independent risks associated with gestational and established diabetes, male sex, parity, duration of gestation, maternal smoking during pregnancy, maternal age, and median income of maternal residential area were obtained and combined in a single logistic model. Maternal smoking was associated with a decreased risk of macrosomia (OR 0.4, 95% CI 0.3-0.5). Established diabetes (OR 6.4, 95% CI 2.7-15.4), gestational diabetes (OR 3.2, 95% CI 2.1-5.1) and male sex of the infant (OR 2.4, 95% CI 2.2-2.7) were associated with an increased risk. Increasing parity was related to an increasing risk from para one (OR 1.4, 95% 1.2-1.6) to para six and greater (OR 3.3, 95% CI 1.5-7.4). Increasing duration of gestation was associated with an increasing risk from 33-36 weeks (OR 0.8, 95% CI 0.5-1.2) to 43-45 weeks (OR 3.3, 95% CI 2.5-4.2). Maternal age, median income of maternal area of residence, and maternal marital status were not significantly associated with macrosomia.     

Intergenerational influences affecting birth outcome. I. Birthweight for gestational age in the children of the 1958 British Birth Cohort

There is considerable literature on intergenerational influences on birthweight. Few studies have been able to investigate such influences on the more basic measures of birthweight for gestational age and gestational age itself. This paper considers fetal growth. The investigations are derived from the 1958 British birth cohort followed from birth to age 33 years. Included were questions on physical and social characteristics of each parent and the grandparents, and birth details of parent and first child. In the present study, fetal growth in non-preterm babies, after adjustment for the known effects of smoking and sex of the child, is explained best by factors relating to the parent's own growth, primarily in utero , but also to adulthood. There are small additional effects of education or social class but not of parent's gestational age. Only 15% of the variability in the child's fetal growth can be explained by the mother's characteristics and ≈ 7% by the father's. Parent's own fetal growth accounts for nearly half of the variability if unadjusted for other factors and nearly a third after adjustment for sex of child, smoking, parental height and weight, maternal age at menarche and paternal age at first birth. Parental fetal growth makes the greatest anthropometric contribution.     

出生体重与分娩方式的变化分析

目的 探讨本院近19年来足月妊娠,头位分娩,无合并症的产妇年龄、孕周、出生体重和分娩方式的变化及意义。方法 26 479例产妇资料被输入计算机,采用SSPS软件进行相关性分析、t检验和卡方检验。结果 随年代递增,产妇年龄逐渐增大,孕周减小,出生体重增加。阴道产率下降,剖宫产率上升,产钳助产率变化无规律。男女婴比例接近,男婴出生体重高于女婴,随年代不同,两者均增长,但增长幅度呈下降趋势。结论 近十几年来,胎儿出生体重逐渐增加,剖宫产率上升,男女婴比例略高于1:1。     

Factors influencing birth weight in newborns of diabetic and non-diabetic women a population based study

Maternal diabetes is known to be related to an increase in birth weight of the offspring. However, the mechanism of the association is not entirely clear. In addition, the contribution of the demographic, obstetric and metabolic factors to birth weight in diabetic mothers is not well defined. All the diabetic women (68 requiring insulin-treatment and 403 on diet alone) and a random sample of 1 in 12 of all non-diabetic women (893 women) who delivered in one regional hospital between March 1987 and June 1988 inclusive, were included in the study. Tests for gestational diabetes are routinely performed in our pregnant women population, thus, the study is a population based one. The mean birth weight of infants of diabetic mothers adjusted for gestational age was higher than in those of non-diabetic mothers. However, no relationship was found between maternal glycosylated hemoglobin measured at delivery and the infants birth weight. Furthermore, at each week of gestation, infants born to diabetic mothers were heavier than the infants of non-diabetic mothers (for weeks 37 to 40, p < 0.05), while no differences were found in glycosylated hemoglobin levels between the two groups at any time. In a multivariate model we showed that after controlling for gestational age, the only factors which independently and significantly affected birth weight in our population were diabetes, ethnic origin, and the parity of the mother. Our findings support the possibility that substances which induce hyperinsulinemia, other than glucose, may be related to the higher birth weight of infants of diabetic mothers.     

The influence of erythrocyte folate and serum vitamin B12 status on birth weight

The extent to which maternal folate and vitamin B12 modulate infant birth weight is unclear. The present study investigated mothers in early gestation (mean 11.5 (sd 5.8) weeks) and neonates, at delivery. Erythrocyte (RBC) folate (mothers: n 683; neonates: n 614) and vitamin B12 (mothers: n 534; neonates: n 614) were measured. Data on smoking habits were available for 44 % of pregnancies (n 443). The relationship between vitamin levels and birth weight standardized for gender and gestational age was investigated, using linear regression and adjusting for possible confounding variables (maternal age, parity). Results are presented as standardized regression coefficients (b). Increasing maternal age was associated with elevated RBC folate (b 0.11 (95 % CI 0.08, 0.15), P<0.001; n 674) and smoking was associated with a decrease in maternal RBC folate (b -1.38 (95 % CI -1.92, -0.86), P=0.001; n 319). Neonatal RBC folate was predicted by maternal RBC folate (b 0.08 (95 % CI 0.04, 0.11), P=0.001; n 315) and maternal vitamin B12 (b 0.08 (95 % CI 0.01, 0.16), P=0.02; n 252). Smoking influenced maternal vitamin B12 status (b -0.88 (95 % CI -1.49, -0.27), P=0.005; n 231). Using univariate regression, smoking significantly influenced infant birth weight (b -2.15 (95 % CI -3.24, -1.04), P<0.001; n 437). However, the effect of smoking on birth weight was statistically non-significant when considered in a multivariate regression model, leaving maternal RBC folate as the only significant predictor of birth weight (b 0.25 (95 % CI 0.08, 0.42), P=0.005; n 145). These findings suggest that maternal folate status is an important determinant of infant birth weight. The combined effects of smoking and reduced RBC status on birth weight require further investigation.     

Offspring preterm birth and birth size are related to long-term risk of maternal diabetes

The aim of the study is to investigate the association between gestational age, birth size, and the long-term risk of maternal diabetes. We conducted a nation-wide prospective follow-up study of the cohort of all Danish women with a singleton delivery in 1982/1983 (index delivery) and no history of diabetes (n = 100,669). Registries were used to extract information on patients with a hospital or outpatient diagnosis of diabetes, subsequent deliveries, and death/emigration in the period from the index delivery until the end of 2006. The association between the maternal risk of diabetes and the index gestational age and index offspring birth size (birth weight adjusted for gestational age) was investigated by using Cox proportional hazards regression models stratified according to young (≤33 years) and old age (>33 years). During a median follow-up period of 24 years, 2,021 women (2.0 %) were diagnosed as having diabetes. The risk of maternal diabetes was positively associated with increasing index birth size and negatively associated with increasing duration of index gestation in both age strata. Among young women, the highest hazard ratios were found for the exposure category of large index offspring birth size (adjusted HR 9.0, 95 % CI 6.17–13.12) and a preterm delivery at 32–37 weeks (adjusted HR 2.22, 95 % CI 1.46–3.40). Offspring preterm birth and large size for gestational age at birth are associated with increased risk of maternal diabetes.     

Are girls more susceptible to the effects of prenatal exposure to tobacco smoke on asthma?

BACKGROUND: Prenatal exposure to tobacco smoke through mother's smoking increases the risk of developing asthma later in life. A recent study suggested that this effect is present only in girls. We explored potential differences in susceptibility between boys and girls. METHODS: We followed all 58,841 Finnish singleton babies born in 1987 through 5 nationwide registries for 7 years and identified all cases of doctor-diagnosed asthma (ICD-9 code 493). The birth registry provided categorical information on the mother's smoking during pregnancy: no smoking (reference), low exposure (<10 cigarettes per day), and high exposure (>10 cigarettes per day). RESULTS: In girls the cumulative incidence of asthma was 0.0245 in the reference group, 0.0310 in the low maternal smoking group (risk difference = 0.0065; 95% CI = 0.0053-0.0076), and 0.0360 in the high maternal smoking group (0.0115; 0.0096-0.0133). The corresponding cumulative incidences for boys were 0.0405, 0.0501 (0.0096; 0.0089-0.0103), and 0.0522 (0.0117; 0.0091-0.0142). In logistic regression analysis adjusting for confounding, the combined effect of male sex and high maternal smoking (compared with female sex and no smoking) was 112% excess risk. This corresponded closely to what would be expected from the additive independent effects of male sex (67% excess risk) and high maternal smoking (44% excess risk). CONCLUSIONS: Effects of maternal smoking during pregnancy on the risk of developing asthma are similar in boys and girls, with no interaction on an additive scale.     

Maternal Smoking, Preeclampsia, and Infant Health Outcomes in New York City, 1995-2003

A number of previous studies have reported an inverse associationbetween maternal smoking and preeclampsia. Additionally, somehave suggested that smokers who develop preeclampsia have worsematernal and fetal outcomes than nonsmokers who develop preeclampsia.The authors examined the relation of smoking to preeclampsiaamong 674,250 singleton pregnancies in New York City between1995 and 2003. Although smoking was associated with a reducedrisk of preeclampsia overall (adjusted odds ratio = 0.88, 95%confidence interval: 0.82, 0.94), no association was found forpreeclampsia superimposed on chronic hypertension (adjustedodds ratio = 1.04, 95% confidence interval: 0.90, 1.21). Furthermore,the apparent protection conferred by maternal smoking was restrictedto women aged 30 years. Contrary to previous reports, the authorsfound evidence of a negative interaction between smoking andpreeclampsia with respect to preterm delivery and birth weight;smokers who developed preeclampsia had a lower risk of pretermdelivery, and a lower adjusted mean difference in birth weight,than would have been expected based on the independent effectsof smoking and preeclampsia. These data suggest that smokingis only protective against preeclampsia without pregestationalhypertension, and even then principally among younger women.Additionally, smokers who develop these disorders have no increasedrisk of adverse birth outcomes relative to nonsmokers who developthe same conditions. birth weight; pre-eclampsia; preterm birth; smoking     

Differences in BMI z-Scores between Offspring of Smoking and Nonsmoking Mothers: A Longitudinal Study of German Children from Birth through 14 Years of Age

Background: Children of mothers who smoked during pregnancy have a lower birth weight but have a higher chance to become overweight during childhood.Objectives: We followed children longitudinally to assess the age when higher body mass index (BMI) z-scores became evident in the children of mothers who smoked during pregnancy, and to evaluate the trajectory of changes until adolescence.Methods: We pooled data from two German cohort studies that included repeated anthropometric measurements until 14 years of age and information on smoking during pregnancy and other risk factors for overweight. We used longitudinal quantile regression to estimate age- and sex-specific associations between maternal smoking and the 10th, 25th, 50th, 75th, and 90th quantiles of the BMI z-score distribution in study participants from birth through 14 years of age, adjusted for potential confounders. We used additive mixed models to estimate associations with mean BMI z-scores.Results: Mean and median (50th quantile) BMI z-scores at birth were smaller in the children of mothers who smoked during pregnancy compared with children of nonsmoking mothers, but BMI z-scores were significantly associated with maternal smoking beginning at the age of 4–5 years, and differences increased over time. For example, the difference in the median BMI z-score between the daughters of smokers versus nonsmokers was 0.12 (95% CI: 0.01, 0.21) at 5 years, and 0.30 (95% CI: 0.08, 0.39) at 14 years of age. For lower BMI z-score quantiles, the association with smoking was more pronounced in girls, whereas in boys the association was more pronounced for higher BMI z-score quantiles.Conclusions: A clear difference in BMI z-score (mean and median) between children of smoking and nonsmoking mothers emerged at 4–5 years of age. The shape and size of age-specific effect estimates for maternal smoking during pregnancy varied by age and sex across the BMI z-score distribution.Citation: Riedel C, Fenske N, Müller MJ, Plachta-Danielzik S, Keil T, Grabenhenrich L, von Kries R. 2014. Differences in BMI z-scores between offspring of smoking and nonsmoking mothers: a longitudinal study of German children from birth through 14 years of age. Environ Health Perspect 122:761–767; http://dx.doi.org/10.1289/ehp.1307139