Is low birth weight in the causal pathway of the association between maternal smoking in pregnancy and higher BMI in the offspring?

Having siblings promotes a more healthy weight status—Whereas only children are at greater risk for higher BMI in later childhood

Background

Birth order and having at least one sibling are known to be associated with an increased risk for development of overweight. However, there are no studies assessing pre- and postnatal factors for developing overweight within families. Therefore, the present study aimed to analyse the association of the mother’s weight gain during pregnancy, prepregnancy BMI, mother’s age at birth, breastfeeding, age gap between siblings, and physical activity together with sibling-related characteristics on the development of overweight in children and adolescents.

Methods

Data were obtained from the longitudinal LIFE Child cohort. The study sample included n = 1932 children, stratified into first-born (n = 578), second-born (n = 608), third-or-later-born single-born siblings (n = 162), only children (n = 526), and twin children (n = 58). Children with chronic or syndromic diseases, born prematurely or from mothers with gestational diabetes were excluded. Data were adjusted for multiple children per family using mixed models. Pregnancy weight gain, prepregnancy BMI and mother’s age were considered prenatal co-variates. Postnatal factors included the duration of breastfeeding and the children’s physical activity level.

Results

Particularly until the onset of puberty, the BMI-SDS differed between single-born siblings, only children and twins, and increased with birth order. Compared to children with siblings, only children exhibited a strong increase in BMI-SDS starting at age nine. A higher age gap between siblings was associated with a higher BMI-SDS in second- and third-or-later-born children. Single-born siblings had the highest rate and duration of breastfeeding. Physical activity was highest in twins and third-or-later-born children and lowest in only children. In a multivariate model, being an only child showed a highly significant association with BMI-SDS.

Conclusion

The present study demonstrated that siblings had a lower BMI-SDS than only children did. For single-born siblings, the association between birth order and increased BMI-SDS seemed to persist only up to 11 years of age.

Prenatal Education Intervention for Increasing Knowledge and Changing Attitude Toward Offspring Obesity Risk Factors

This pre- and post-test quasi-experimental design study pilot tested an educational intervention designed to increase knowledge of and change attitudes toward prenatal factors that increase risk of childhood offspring obesity in 36 pregnant women. Educational intervention content included monitoring blood glucose, gestational weight gain in pregnancy, healthy lifestyle choices, and breastfeeding. Education intervention delivery method included: Verbal, written, and video. Participants’ knowledge improved after the intervention for most topics (p = .03–.000). Their attitude score also differed before and after intervention (p = .002). Video delivery mode was the most useful, attractive, and most helpful method. This study showed an education intervention could potentially increase pregnant women’s knowledge and attitudes toward offspring obesity risk factors.

Pan-risk factor for a comprehensive cardiovascular health management

Cardiovascular diseases (CVDs) have become the leading cause of death in China. CVDs are mainly caused by multiple well-known modifiable risk factors that are affected by socioeconomic and environmental determinants, lifestyle and behavioral choices, and familial and genetic predispositions. With more risk factors proved to be associated with CVD occurrence, the concept "pan-risk factor" is proposed in this review to indicate all discovered and yet-to-be-discovered CVD risk factors for comprehensive primary prevention of CVD. Recognizing more factors and their roles in CVD development and progression is the first step in reducing the ever-increasing burden of CVD. This review is an overview of the pan-risk factor whose associations with CVD outcomes have been established. Along with the accumulation of scientific evidence, an increasing number of risk factors will be discovered and included in the list of pan-risk factors.

Socioeconomic disparities and infancy growth trajectory: a population-based and longitudinal study

Background

The association of low socioeconomic status (SES) with childhood and adolescent obesity has been reported. It is unknown whether low SES affects body mass index (BMI) growth trajectory in the first 12 mo of life. Moreover, accelerated growth as a compensatory mechanism for low birth weight (LBW) during infancy, is an important predictor of later obesity. The aim of the present study was to examine the association of low SES with infancy BMI growth rate and trajectory for LBW and normal birth weight (NBW) infants.

Methods

From September 2012 to October 2014, a total of 387 infants in this longitudinal study was subjected to repeated measures of weight and length from birth to 12 mo in Hefei. Generalized growth mixture modeling was used to classify the infancy BMI growth trajectories. Differences in infancy BMI z score (zBMI) and BMI growth rate between low SES and high SES were estimated based on linear regression after adjusting for several confounders including maternal age, pregnancy BMI, physical activity during pregnancy, paternal BMI as well as alcohol use, paternal smoking status, breastfeeding duration and delivery mode.

Results

Infancy BMI trajectories in this study were classified into three categories: rapid growth (class 1), normal growth (class 2) and slow growth (class 3). Low SES infants had the higher zBMI than high SES infants for LBW group at age 6 mo [zBMI difference with 95% CI at 6 mo: 0.28(0.03, 0.53); at 12 mo: 0.21(0.01, 0.43)]. Low SES infants had more rapid zBMI growth rate than those with high SES for low birth weight between 0 and 6 months. Controlling for the confounders, these associations remained robust. We found the lower SES in the rapid growth group.

Conclusions

These findings highlighted the impact of low SES on increasing BMI and accelerated growth during early infancy. Health care and relatively optimal family environment in the first 12 mo of life, especially for LBW infants, are benefit to shape the better infancy growth trajectory.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02995-4.

Association between maternal smoking during pregnancy and offspring overweight in U.S.-born children

BACKGROUND

The criticism of the literature on smoking during pregnancy and offspring overweight was the confounding from postnatal factors. Interaction between gestational age and prenatal maternal smoking has not yet assessed.

METHODS

We used the Third National Health and Nutrition Examination Survey (1988-1994), linked with natality files of US-born singletons aged 2 to 6 years. A body mass index in the 85th percentile or higher were considered overweight, including obesity. Gestational age was dichotomized as preterm (<37 weeks, n = 240) or full-term (n = 2125). Smoking status during pregnancy was ascertained by a questionnaire-based interview during National Health and Nutrition Examination Survey.

RESULTS

The prevalence of offspring overweight and obesity combined was 17.3% (SE = 1.3%). And 24.0% (1.3%) of mothers smoked while pregnant. A significant interaction was observed between maternal smoking and gestational age. In preterm children, a higher prevalence of overweight (34.3% [6.7%]) was found among the offspring of smoking mothers compared to non-smoking mothers (15.8% [3.6%]). After adjustment for socio-demographics, prenatal and postnatal factors, in preterm born offspring, the odds ratio of being born to smoking mothers was 2.46 (95% confidence intervals: 1.13-5.37) among children with overweight/obesity compared to children with healthy weight born to non-smoking mothers. In full-term children, the OR of being born to smoking mothers was 0.72 (0.50-1.03) among offspring with overweight/obesity relative to offspring with healthy weight born to non-smoking mothers.

CONCLUSIONS

Maternal smoking during pregnancy was strongly associated with offspring overweight and obesity in preterm births after control for postnatal factors. Preterm children of smoking mothers should be prioritized for obesity prevention.

Body mass index changes: an assessment of the effects of age and gender using the e-norms method

Background

To validate e-norms methodology in establishing a reference range for body mass index measures. A new method, the extrapolated norms (e-norms) method of determining normal ranges for biological variables is easy to use and recently was validated for several biological measurements. We aimed to determine whether this new method provides BMI results in agreement with established traditionally collected BMI values.

Methods

We applied the e-norms method to BMI data from 34,384 individuals and compared the ranges derived from this method with those from a large actuarially based study and explored differences in the normal range by gender, and age.

Results

The e-norms derived range of healthy BMI in adults is from 22.7 to 30.6, and showed that BMI is consistently higher in men than in women and increases with age, except in subjects aged 80–98 years in whom healthy BMI appears to be lower.

Conclusions

Our e-norms derived healthy BMI ranges agree with traditionally obtained actuarially based methods, supporting the validity and ease of use of our method.

Maternal body mass index, smoking status and small for gestational age: an Australian retrospective cohort study

OBJECTIVES

Both maternal body mass index (BMI) and smoking during pregnancy have been associated with a range of adverse maternal and infant birth outcomes. This study aimed to identify whether these independent variables had an interacting relationship with small for gestational age in an Australian obstetric cohort.

STUDY DESIGN

A retrospective cohort design used data from the Birthing Outcomes System of a major tertiary hospital in Australia.

METHODS

A total of 14,487 singleton births between January 2008 and December 2013 were included in the analysis. Chi-squared tests and one-way analysis of variance were used for the comparison of categorical and continuous variables, respectively. Adjusted odds ratios (AORs) were calculated to determine the association of smoking status with the outcome variable of interest, and these are reported for each maternal BMI category.

RESULTS

Of the 14,487 women, 716 (4.9%) were underweight (BMI ≤18 kg/m²), 7268 (50.2%) had healthy weight (BMI = 19-24 kg/m²), 3658 (25.3%) were overweight (BMI = 25-29 kg/m²), 1558 (10.8%) had class I obesity (BMI = 30-34 kg/m²), 711 (4.9%) had class II obesity (BMI = 35-39 kg/m²) and 576 (3.9%) had class III obesity (BMI = 40+ kg/m²). Of all women, 10.8% reported being current smokers, 82.0% reported to have never smoked and 4.0% reported to have stopped smoking during or before pregnancy. Smokers with a BMI ≥40 kg/m² were 4.5 (AOR = 4.508; 95% confidence interval: 2.068-9.828) times more likely to give birth to a small-for-gestational-age infant than non-smokers within the same BMI category. This increased risk was not observed in women who ceased smoking before or during pregnancy.

CONCLUSIONS

Our study supports the efficacy of antismoking policies within maternal public health. In addition, greater support with respect to smoking cessation is indicated for women during pregnancy with an elevated BMI.

An educational intervention to prevent overweight in pre-school years: a cluster randomised trial with a focus on disadvantaged families

BACKGROUND

Early prevention is a promising strategy for reducing obesity in childhood, and Early Years settings are ideal venues for interventions. This work evaluated an educational intervention with the primary aim of preventing overweight and obesity in pre-school children.

METHODS

A pragmatic, cluster randomised trial with a parallel, matched-pair design was undertaken. Interventions were targeted at both the cluster (Early Years' Centres, matched by geographical area) and individual participant level (families: mother and 2-year old child). At the cluster level, a staff training intervention used the educational resource Be Active, Eat Healthy. Policies and provision for healthy eating and physical activity were evaluated at baseline and 12-months. The intervention at participant level was the Healthy Heroes Activity Pack: delivered over 6 months by Centre staff to promote healthy eating and physical activity in a fun, interactive way. Child and parent height and weight were measured at four time-points over 2 years. The trial primary outcome was the change in BMI z-score of the child between ages 2 and 4 years. Secondary outcomes consisted of parent-reported measures administered at baseline and two-year follow-up.

RESULTS

Five pairs of Early Years' Centres were recruited. Four pairs were analysed as one Centre withdrew (47 intervention families; 34 control families). At the cluster level, improvement in Centre policies and practices was similar for both groups (p = 0.830). At the participant level, the intervention group reduced their mean BMI z-score between age 2 and 4 years (p = 0.002; change difference 0.49; 95% CI 0.17 to 0.80) whereas the control group showed increasing BMI z-score throughout. Changes in parent-reported outcomes and parent BMI (p = 0.582) were similar in both groups.

CONCLUSIONS

The Healthy Heroes educational resource deterred excess weight gain in pre-school children from poor socioeconomic areas. With training, Early Years' staff can implement the Healthy Heroes programme.

TRIAL REGISTRATION

ISRCTN22620137 Registered 21st December 2016.

Impact of Carers' Smoking Status on Childhood Obesity in the Growing up in Ireland Cohort Study

Childhood obesity is a growing concern worldwide. The association between childhood obesity and maternal smoking and/or paternal smoking has been reported. However, few studies have explored the association between childhood obesity and exposure to carers’ smoking status. This study aimed to assess the impact of carers’ smoking status on childhood obesity in a cohort of children enrolled in the Growing up in Ireland (GUI) study. Participants from the GUI infant cohort were categorized into four groups based on their exposure status: Neither caregiver smoked (60.4%), only primary caregiver smoked (13.4%), both caregivers smoked (10.9%). Exposure to primary carers’ smoking (98% are biological mothers) was found to be significantly associated with childhood overweight/obesity at age three (Odds Ratio: 1.30, 95% CI: 1.17–1.46) and at age five (OR: 1.31, 95% CI: 1.16–1.49). Exposure to both carers’ smoking status was significantly associated with increased odds of childhood overweight/obesity across both waves. These findings emphasize the health burden of childhood obesity that may be attributable to maternal smoking postnatally and through early childhood in Ireland.

Effect of passive exposure to cigarette smoke on blood pressure in children and adolescents: a meta-analysis of epidemiologic studies

Background

Hypertension is an emerging disease in children and adolescents resulting in future morbidities. Cigarette smoking is one of the most studied contributing factors in this regard; however, there are contradictory results among different studies. Therefore, the present meta-analysis tends to assess the relationship between passive exposure to cigarette smoke and blood pressure in children and adolescents.

Method

Medline, Embase, Scopus, EBSCO, and Web of Sciences were systematically reviewed for observational studies up to May, 2017, in which the relationship between cigarette smoking and hypertension were assessed in children and adolescents. The meta-analysis was performed with a fixed effect or random effects model according to the heterogeneity.

Results

Twenty-nine studies were included in present meta-analysis incorporating 192,067 children and adolescents. Active smoking (pooled OR = 0.92; 95% CI: 0.79 to 1.05) or passive exposure to cigarette smoke (pooled OR = 1.01; 95% CI: 0.93 to 1.10) were not associated with developing hypertension in the study population. Despite the fact that active cigarette smoking did not significantly affect absolute level of systolic and diastolic blood pressure, it was shown that passive exposure to cigarette smoke leads to a significant increase in absolute level of systolic blood pressure (pooled coefficient = 0.26; 95% CI: 0.12 to 0.39).

Conclusion

Both active and passive cigarette smoking were not associated with developing hypertension in children and adolescents. However, passive cigarette smoke was associated with higher level of systolic blood pressure in children and adolescents.

Maternal smoking during pregnancy and offspring body mass index and overweight: a systematic review and meta-analysis

Abstract: The present study aimed to conduct a systematic review and meta-analysis to evaluate the evidence on the association of maternal smoking during pregnancy with offspring body composition in childhood, adolescence and adulthood. MEDLINE, Web of Science and LILACS databases were searched. Reference lists were also screened. We included original studies, conducted in humans, that assessed the association of maternal smoking during pregnancy with offspring body mass index (BMI) and overweight in childhood, adolescence and adulthood, published through May 1st, 2018. A meta-analysis was used to estimate pooled effect sizes. The systematic review included 64 studies, of which 37 evaluated the association of maternal smoking during pregnancy with overweight, 13 with BMI, and 14 evaluated both outcomes. Of these 64 studies, 95 measures of effect were extracted and included in the meta-analysis. We verified that the quality of evidence across studies regarding maternal smoking in pregnancy and overweight and BMI of offspring to be moderate and low, respectively. Most studies (44 studies) were classified as moderate risk bias. Heterogeneity among studies included was high and, in the random-effects pooled analysis, maternal smoking during pregnancy increased the odds of offspring overweight (OR: 1.43, 95%CI: 1.35; 1.52) and mean difference of BMI (β: 0.31, 95%CI: 0.23; 0.39). In conclusion, offspring of mothers who smoked during pregnancy have higher odds of overweight and mean difference of BMI, and these associations persisted into adulthood.

Associations of maternal type 1 diabetes with childhood adiposity and metabolic health in the offspring: a prospective cohort study

AIMS/HYPOTHESIS

Exposure to an intrauterine hyperglycaemic environment has been suggested to increase the offspring's later risk for being overweight or having metabolic abnormalities, but conclusive evidence for pregnancies affected by maternal type 1 diabetes is still lacking. This study aims to analyse the relationship between maternal type 1 diabetes and the offspring's metabolic health and investigate whether birthweight and/or changes in the offspring's metabolome are in the potential pathway.

METHODS

We analysed data from 610 and 2169 offspring having a first-degree relative with type 1 diabetes from the TEENDIAB and BABYDIAB/BABYDIET cohorts, respectively. Anthropometric and metabolic outcomes, assessed longitudinally at 0.3-18 years of age, were compared between offspring of mothers with type 1 diabetes and offspring of non-diabetic mothers but with fathers or siblings with type 1 diabetes using mixed regression models. Non-targeted metabolomic measurements were carried out in 500 individuals from TEENDIAB and analysed with maternal type 1 diabetes and offspring overweight status.

RESULTS

The offspring of mothers with type 1 diabetes had a higher BMI SD score (SDS) and an increased risk for being overweight than the offspring of non-diabetic mothers (e.g. OR for overweight status in TEENDIAB 2.40 [95% CI 1.41, 4.06]). Further, waist circumference SDS, fasting levels of glucose, insulin and C-peptide, and insulin resistance and abdominal obesity were significantly increased in the offspring of mothers with type 1 diabetes, even when adjusted for potential confounders and birthweight. Metabolite patterns related to androgenic steroids and branched-chain amino acids were found to be associated with offspring's overweight status, but no significant associations were observed between maternal type 1 diabetes and metabolite concentrations in the offspring.

CONCLUSIONS/INTERPRETATION

Maternal type 1 diabetes is associated with offspring's overweight status and metabolic health in later life, but this is unlikely to be caused by alterations in the offspring's metabolome.

The Effect of Cigarette Smoking during Pregnancy on Endocrine Pancreatic Function and Fetal Growth: A Pilot Study

Introduction

Cigarette smoking in pregnancy is a common cause of fetal growth restriction. We aimed to investigate endocrine pancreatic function of mother–infant dyads in relation to cigarette smoking, as a possible mechanism for the poor fetal growth.

Methods

Prospective study of smoking mothers (10 cigarettes or more per day, self-reported to the midwife) and non-smoker control mothers during their first pregnancy. Insulin, glucose, C-peptide, HbA1C, fructosamine, prolactin, serotonin, and cortisol were measured in maternal blood at 24–26 weeks and in umbilical cord blood at birth. Cotinine was also measured in cord blood.

Results

Of 37 smokers and 36 non-smokers recruited, cord blood was obtainable from 38 babies (19 in each group). In utero cigarette exposure was associated with lower birthweight (3,035 ± 490 versus 3,405 ± 598 g, p = 0.005), with linear modeling of the smoking cohort showing a 41 g reduction for every increase of one cigarette smoked per day (95% CI −71 to −11 g, p = 0.010). There were no differences between groups in indices of maternal or perinatal endocrine pancreatic dysfunction. Heavier smoking independently correlated with higher maternal fasting levels of glucose (p = 0.044) and C-peptide (p = 0.011). We did not observe any significant associations between the daily number of cigarettes and any of the cord blood parameters. We also looked for differences between cohorts based on infant gender. Serotonin levels were higher in smoking mothers with male fetuses (p = 0.01 to p = 0.004).

Conclusion

Endocrine pancreatic dysfunction does not appear to be a major contributing factor to nicotine-associated fetal growth restriction. The higher serotonin levels in smoking mothers carrying male infants is of uncertain significance but could be a manifestation of gender differences in susceptibility to the long-term effects of cigarette smoking.

Somatic growth in the first six months of life of infants exposed to maternal smoking in pregnancy

Background

Some studies suggest a relationship between maternal smoking during pregnancy and not only intrauterine fetal growth restriction or low birth weight, but also with changes in the postnatal growth and development. The objective of the present study was to investigate the effects of smoking during pregnancy on infants growth in the first 6 months of life compared with a control group and a group with idiopathic intrauterine growth restriction.

Methods

Longitudinal observational study using a convenience sample of newborns divided into three groups: infants of smoking mothers (tobacco), with idiopathic intrauterine growth restriction (IUGR) and a control group. The sample was selected from two hospitals in Porto Alegre, located in southern Brazil, between 2011 and 2015. Newborns were evaluated at birth, 7 and 15 days, and in the first, third, and sixth month. Anthropometric measures were weight, length and head circumference. The growth indicators used were expressed as z-scores. The analyses were performed using the generalized estimating equation method.

Results

The sample included 273 mother/newborn pairs: 86 tobacco group, 34 IUGR group, and 153 control group. In terms of weight at birth, all groups differed significantly (p < 0.001). The birth length of tobacco and control groups were similar, but the IUGR group was lower than both (p < 0.001). We found no differences in growth trajectory between tobacco and control group, but there were differences in the growth of the IUGR group when compared with the other groups. At 6 months of age, all groups had similar anthropometric measurements.

Conclusion

Intrauterine growth restriction had major impact on the growth trajectory of the infants studied, regardless of other factors, such as smoking and diet.

Analysis of hospital cost outcome of DHA-rich fish-oil supplementation in pregnancy: Evidence from a randomized controlled trial

OBJECTIVE

Recent research emphasized the nutritional benefits of omega-3 long chain polyunsaturated fatty acids (LCPUFAs) during pregnancy. Based on a double-blind randomised controlled trial named "DHA to Optimize Mother and Infant Outcome" (DOMInO), we examined how omega 3 DHA supplementation during pregnancy may affect pregnancy related in-patient hospital costs.

METHOD

We conducted an econometric analysis based on ordinary least square and quantile regressions with bootstrapped standard errors. Using these approaches, we also examined whether smoking, drinking, maternal age and BMI could influence the effect of DHA supplementation during pregnancy on hospital costs.

RESULTS

Our regressions showed that in-patient hospital costs could decrease by AUD92 (P<0.05) on average per singleton pregnancy when DHA supplements were consumed during pregnancy. Our regression results also showed that the cost savings to the Australian public hospital system could be between AUD15 - AUD51 million / year.

CONCLUSION

Given that a simple intervention like DHA-rich fish-oil supplementation could generate savings to the public, it may be worthwhile from a policy perspective to encourage DHA supplementation among pregnant women.

Association of early and late maternal smoking during pregnancy with offspring body mass index at 4 to 5 years of age

The objective was to investigate the association between early and late maternal smoking during pregnancy on offspring body mass index (BMI). We undertook a retrospective cohort study using linked records from the Women’s and Children’s Health Network in South Australia. Among a cohort of women delivering a singleton, live-born infants between January 2000 and December 2005 (n=7658), 5961 reported not smoking during pregnancy, 297 reported quitting smoking during the first trimester of pregnancy, and 1400 reported continued smoking throughout pregnancy. Trained nurses measured the height and weight of the children at preschool visits in a state-wide surveillance programme. The main outcome measure was age- and sex-specific BMI z-score. At 4 to 5 years, mean (s.d.) BMI z-score was 0.40 (1.05), 0.60 (1.07) and 0.65 (1.18) in children of mothers who reported never smoking, quitting smoking and continued smoking during pregnancy, respectively. Compared with the group of non-smokers, both quitting smoking and continued smoking were associated with an increase in child BMI z-score of 0.15 (95% confidence interval: 0.01–0.29) and 0.21 (0.13–0.29), respectively. A significant dose–response relationship was also observed between the number of cigarettes smoked per day on average during the second half of pregnancy and the increase in offspring BMI z-score (P<0.001). In conclusion, any maternal smoking in pregnancy, even if mothers quit, is associated with an increase in offspring BMI at 4 to 5 years of age.

In utero exposure to cigarette smoking, environmental tobacco smoke and reproductive hormones in US girls approaching puberty

BACKGROUND/AIMS

Evidence is unclear whether prenatal smoking affects age at menarche and pubertal development, and its impact upon hormones has not been well studied. We aim to identify potential pathways through which prenatal smoking and environmental tobacco smoke (ETS) affect reproductive hormones in girls approaching puberty.

METHODS

We examined the association between prenatal smoking, current ETS and luteinizing hormone (LH) and inhibin B (InB) in 6- to 11-year-old girls in the 3rd National Health and Nutrition Examination Survey, 1988-1994. Parents/guardians completed interviewer-assisted questionnaires on health and demographics at the time of physical examination. Residual blood samples were analyzed for reproductive hormones in 2008.

RESULTS

Of 660 girls, 19 and 39% were exposed to prenatal smoke and current ETS, respectively. Accounting for multiple pathways in structural equation models, prenatally exposed girls had significantly lower LH (β = -0.205 log-mIU/ml, p < 0.0001) and InB (β = -0.162, log-pg/ml, p < 0.0001). Prenatal smoking also influenced LH positively and InB negatively indirectly through BMI-for-age. ETS was positively associated with LH, but not with InB.

CONCLUSION

Exposure to maternal smoking may disrupt reproductive development manifesting in altered hormone levels near puberty.

Independent and joint effects of prenatal maternal smoking and maternal exposure to second-hand smoke on the development of adolescent obesity: a longitudinal study

AIM

To examine associations of prenatal maternal smoking and second-hand smoke (SHS) exposure with the development of adolescent obesity.

METHODS

Longitudinal data (1991-2007) from National Institute of Child Health and Human Development Study of Early Child Care and Youth Development involving mothers that smoked and or exposed to SHS during the year before birth were analysed. Adolescent obesity in ages 12.0-15.9 years was defined as a BMI ≥ 95th percentile. Generalised estimating equations (GEE) were used for the analyses.

RESULTS

Obesity was more prevalent among adolescents whose mothers smoked or had SHS exposure than those that did not smoke or exposed to SHS. After adjusting for maternal and child factors, GEE models showed that odds of adolescent obesity increased with prenatal maternal smoking (OR = 1.57, 95% CI = 1.03-2.39) and SHS exposure (OR = 1.53, 95% CI = 1.04-2.27). The odds for obesity increased more than two times among adolescents exposed to both maternal smoking and SHS (OR = 2.10, 95% CI = 1.24, 3.56) compared with those without exposure. Additionally, not breastfeeding, maternal obesity, and longer screen viewing hours per day were associated with increased odds of obesity.

CONCLUSIONS

There is possibly a long-term joint effect of prenatal maternal smoke (smoking and SHS) exposure on obesity among adolescent offspring, and the effect is independent of birthweight. These findings suggest that adolescent obesity could possibly be curtailed with the development and promotion of smoking cessation programmes for families during the year before birth.

Risk of childhood overweight after exposure to tobacco smoking in prenatal and early postnatal life

OBJECTIVE

To investigate the association between exposure to mothers smoking during prenatal and early postnatal life and risk of overweight at age 7 years, while taking birth weight into account.

METHODS

From the Danish National Birth Cohort a total of 32,747 families were identified with available information on maternal smoking status in child's pre- and postnatal life and child's birth weight, and weight and height at age 7 years. Outcome was overweight according to the International Obesity Task Force gender and age specific body mass index. Smoking exposure was categorized into four groups: no exposure (n = 25,076); exposure only during pregnancy (n = 3,343); exposure only postnatally (n = 140); and exposure during pregnancy and postnatally (n = 4,188). Risk of overweight according to smoking status as well as dose-response relationships were estimated by crude and adjusted odds ratios using logistic regression models.

RESULTS

Exposure to smoking only during pregnancy, or both during pregnancy and postnatally were both significantly associated with overweight at 7 years of age (OR: 1.31, 95% CI: 1.15-1.48, and OR: 1.76, 95% CI: 1.58-1.97, respectively). Analyses excluding children with low birth weight (<2,500 gram) revealed similar results. A significant prenatal dose-response relationship was found. Per one additional cigarette smoked per day an increase in risk of overweight was observed (OR: 1.02, 95% CI: 1.01-1.03). When adjusting for quantity of smoking during pregnancy, prolonged exposure after birth further increased the risk of later overweight in the children (OR 1.28, 95% CI:1.09-1.50) compared with exposure only in the prenatal period.

CONCLUSIONS

Mother's perinatal smoking increased child's OR of overweight at age 7 years irrespective of birth weight, and with higher OR if exposed both during pregnancy and in early postnatal life. Clear dose-response relationships were observed, which emphasizes the need for prevention of any tobacco exposure of infants.

Parental smoking and childhood obesity: higher effect estimates for maternal smoking in pregnancy compared with paternal smoking--a meta-analysis

BACKGROUND

Some studies reported similar effect estimates for the impact of maternal smoking in pregnancy and paternal smoking on childhood obesity, whereas others suggested higher effects for maternal smoking. We performed a meta-analysis to compare the effect of in utero exposure to maternal smoking and that of paternal or household smoking exposure in utero or after birth with mutual adjustment.

METHODS

Meta-analysis of observational studies identified in MEDLINE, EMBASE and Web of Knowledge published in 1900-2013. Study inclusion criterion was assessment of the association of maternal smoking during pregnancy and paternal or household smoking (anyone living in the household who smokes) at any time with childhood overweight and obesity. The analyses were based on all studies with mutually adjusted effect estimates for maternal and paternal/household smoking applying a random-effects model.

RESULTS

Data for 109,838 mother/child pairs were reported in 12 studies. The pooled odds ratios (ORs) for overweight 1.33 [95% confidence interval (CI) 1.23;1.44] (n=6, I2=0.00%) and obesity 1.60 (95% CI 1.37;1.88) (n=4, I2=32.47%) for maternal smoking during pregnancy were higher than for paternal smoking: 1.07 (95% CI 1.00;1.16) (n=6, I2=41.34%) and 1.23 (95% CI 1.10;1.38) (n=4, I2=14.61%), respectively. Similar estimates with widely overlapping confidence limits were found for maternal smoking during pregnancy and childhood overweight and obesity: 1.35 (95% CI 1.20;1.51) (n=3, I2=0.00%) and 1.28 (95% CI 1.07;1.54) (n=3, I2=0.00%) compared with household smoking 1.22 (95% CI 1.06;1.39) (n=3, I2=72.14%) and 1.31 (95% CI 1.15;1.50)] (n=3, I2=0.00%).

CONCLUSIONS

Higher effect estimates for maternal smoking in pregnancy compared with paternal smoking in mutually adjusted models may suggest a direct intrauterine effect.

Association of pre- and post-natal parental smoking with offspring body mass index: an 8-year follow-up of a birth cohort

BACKGROUND

Although many epidemiological studies have shown an association between maternal smoking during pregnancy and offspring overweight, it is still under debate whether intrauterine tobacco smoke exposure directly affects offspring obesity or if the association is rather due to confounding by lifestyle factors.

OBJECTIVES

The association of parental smoking habits at pre- and post-natal periods with offspring body mass index (BMI) was investigated, whereas maternal smoking during pregnancy was validated by cord serum cotinine measurements.

METHODS

Multivariable linear regression analysis, based on the German Ulm Birth Cohort Study of 1045 children born in 2000 with annual/biennial follow-up until the age of 8 years (n = 609), was conducted.

RESULTS

BMI of offspring from mothers who smoked during pregnancy and non-smoking mothers differed significantly at 8 years. Maternal smoking during pregnancy was associated with an increase in BMI of 0.73 kg m(-2) [95% confidence interval: 0.21-1.25] in 8-year-old children after adjustment for multiple potential confounding variables. Both pre- and post-natal smoking of fathers (0.34 [0.01-0.66]/0.45 [0.08-0.81]) and of both parents (1.03 [0.43-1.63]/0.56 [0.14-0.98]) were likewise significantly associated with offspring BMI.

CONCLUSIONS

The observed patterns suggest that residual confounding by living conditions in smoking families rather than specific intrauterine exposure to tobacco smoke may account for the increased risk of offspring overweight.

Classification tree analyses reveal limited potential for early targeted prevention against childhood overweight

OBJECTIVE

Whether specific combinations of risk factors in very early life might allow identification of high-risk target groups for overweight prevention programs was examined.

DESIGN AND METHODS

Data of n = 8981 children from the German KiGGS study were analyzed. Using a classification tree approach, predictive risk factor combinations were assessed for overweight in 3-6, 7-10, and 11-17-year-old children.

RESULTS

In preschool children, the subgroup with the highest overweight risk were migrant children with at least one obese parent, with a prevalence of 36.6 (95% confidence interval or CI: 22.9, 50.4)%, compared to an overall prevalence of 10.0 (8.9, 11.2)%. The prevalence of overweight increased from 18.3 (16.8, 19.8)% to 57.9 (46.6, 69.3)% in 7-10-year-old children, if at least one parent was obese and the child had been born large-for-gestational-age. In 11-17-year-olds, the overweight risk increased from 20.1 (18.9, 21.3)% to 63.0 (46.4, 79.7)% in the highest risk group. However, high prevalence ratios were found only in small subgroups, containing <10% of all overweight cases in the respective age group.

CONCLUSIONS

Our results indicate only a limited potential for early targeted preventions against overweight in children and adolescents.

The Rotterdam Study: 2014 objectives and design update

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

Prenatal Exposure to Maternal Cigarette Smoke and Offspring Risk of Excess Weight Is Independent of Both Birth Weight and Catch-Up Growth

Prenatal exposure to maternal cigarette smoke (PEMCS) is one of the most common insults to the developing fetus and has consistently emerged as an important risk factor for excess weight in the offspring. However, no consensus exists on the mechanism of action or duration of impact. This study seeks to further examine the role of PEMCS on overweight status of children up to age 10. Mother and child pairs (n=1183) were analysed from the Québec Longitudinal Study of Child Development (QLSCD) (1998–2010). Multivariable logistic regression models were used to control for confounders and assess mediation. PEMCS was associated with overweight status at age 10 (OR: 1.70; 95% CI: 1.20–2.43) after adjustment for early life exposures and childhood behaviours. This relationship remained robust after adjustment for birth weight and catch-up growth. Other significant predictors included APGAR score, mother’s immigrant and weight status, family type and child energy intake. The elevated risk of excess weight among the offspring of smoking mothers was not accounted for by other known determinants, and PEMCS appears to play a role independent of birth weight and catch-up growth. Our research suggests that young mothers may be an important audience for targeting preventive strategies.

Interactions of genetic and environmental risk factors with respect to body fat mass in children: results from the ALSPAC study

OBJECTIVE

To evaluate if percentile-specific effects of genetic, environmental and lifestyle obesity risk factors on body mass index (BMI) might reflect gene-environment interactions with respect to the development of overweight.

DESIGN AND METHODS

Retrospective study with data of 2,346 children from the Avon Longitudinal Study of Parents and Children (ALSPAC), using quantile regression with body fat mass index (FMI) for children at the age of 9 years as outcome variable. We assessed interactions of an "obesity-risk-allele-score" with environmental and nutritional factors.

RESULTS

There was no evidence of interactions between the obesity-risk-allele score and the environmental variables except for maternal overweight. However, we found a significant interaction with respect to intake of mono- and polyunsaturated fatty acids at the age of 7. In children with low intake, genetic risk was associated with increasing effect sizes by FMI percentile.

CONCLUSIONS

Our results suggest an interaction between a low dietary content of unsaturated fatty acids and genetic risk factors for overweight on FMI. This effect is likely to be stronger in children with higher FMI.

Parental smoking during pregnancy and risk of overweight and obesity in the daughter

Objective

Emerging evidence suggests that prenatal exposures may affect long-term health outcomes. In utero exposure to smoking is associated with an increased risk of overweight and obesity in children and adolescents. However, few studies have examined how prenatal exposure to parental smoking influences risk of obesity in adulthood and whether these associations are independent of childhood and adolescent adiposity. The aim of the current study was to investigate whether prenatal exposure to parental smoking influences body size in adulthood and whether any association may be mediated by childhood and adolescent body size.

Methods

We investigated the association between parental smoking during pregnancy and risk of overweight and obesity in adulthood and at age 18, and adiposity during childhood among 35,370 participants in the Nurses’ Health Study II. Data on smoking during pregnancy and socioeconomic variables were provided by the mothers, and anthropometric data and adult risk factors were reported by participants.

Results

After adjustment for socioeconomic and behavioral variables, maternal smoking during pregnancy was associated with adiposity at ages 5–10, age 18, and during adulthood. For age 18 overweight the ORs (95% CIs) for 1–14, 15–24, and 25+cigarettes/day were 1.13 (1.18–1.50), 1.40 (1.20–1.64), and 1.15 (0.79–1.69) and for obesity were 1.41 (1.14–1.75), 1.69 (1.31–2.18), and 2.36 (1.44–3.86). The corresponding ORs (95% CIs) for obesity in adulthood were 1.26 (1.16–1.37), 1.46 (1.30–1.63), and 1.43 (1.10–1.86). Risk of adiposity was not increased among daughters whose mothers stopped smoking during the first trimester (OR [95% CI] for overweight (1.03 [95% CI 0.90–1.17] and obesity (1.12 [95% CI 0.97–1.30]). Women whose fathers smoked during pregnancy were also at increased risk of overweight and obesity in adulthood with covariate-adjusted ORs (95% CIs) for obesity of 1.19 (1.11–1.29) for 1–14 cigarettes/day, 1.27 (1.18–1.37) for 15–24 cigarettes/day, and 1.40 (1.27–1.54) for 25+ cigarettes/day compared to fathers who did not smoke (p_trend<0.0001). Paternal smoking during pregnancy was also associated with an increased risk of obesity at age 18 among those whose fathers smoked 15 or more cigarettes/day but was not associated with childhood body size.

Conclusions

Maternal smoking during pregnancy was associated in a dose-response manner with overweight and obesity in the daughter through adolescence and adult life. Smoking cessation during the first trimester appears to mitigate this excess risk.

Paternal smoking was also associated with risk of overweight and obesity of the adult daughter and this association persisted after adjustment for maternal smoking.

Perinatal and early childhood factors for overweight and obesity in young Canadian children

BACKGROUND

This study assessed potential early-life factors and their interrelationships with obesity among young Canadian children.

METHODS

Data from a nationally representative sample of children aged 6 to 11 years in the Canadian Health Measures Survey were analyzed. The associations of perinatal and early childhood behaviours and socio-economic factors with overweight or obesity were evaluated using multivariate logistic regression models. Adjusted population attributable risk fractions (PARFs) were calculated using multivariate logistic regression models.

RESULTS

Of 968 term-born children, 21% were overweight and another 13% were obese. Maternal smoking during pregnancy (adjusted odds ratio, 2.26; 95% confidence interval, 1.23-4.15) was positively associated with obesity. This association was mediated by birth weight (suppression effect); once controlled, the strength of the association between smoking and child obesity increased by 12%. Birth weight per 100 g (1.05; 1.005-1.09) was significantly associated with obesity. Exclusive breastfeeding for 6 months (0.44; 0.31-0.61), adequate sleep hours (0.39; 0.16-0.94) and being physically active (0.50; 0.26-0.93) were found to be protective. Breastfeeding, whether exclusive or not, significantly reduced obesity risk among children whose mothers never smoked in pregnancy. PARFs indicated that 24.4%, 11.5%, 11.3% and 6.0% prevalent cases of child obesity might be prevented by exclusive breastfeeding, smoking cessation during pregnancy, adequate sleep during childhood, and avoiding high birth weight, respectively.

CONCLUSIONS

This study identified multiple perinatal and childhood factors associated with obesity in young Canadian children. Effective prevention strategies targeting four modifiable maternal and child risk factors may reduce childhood obesity by up to 54% in Canada.

The Generation R Study: design and cohort update 2012

The Generation R Study is a population-based prospective cohort study from fetal life until adulthood. The study is designed to identify early environmental and genetic causes and causal pathways leading to normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on six areas of research: (1) maternal health; (2) growth and physical development; (3) behavioural and cognitive development; (4) respiratory health and allergies; (5) diseases in childhood; and (6) health and healthcare for children and their parents. Main exposures of interest include environmental, endocrine, genetic and epigenetic, lifestyle related, nutritional and socio-demographic determinants. In total, n = 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. Response at baseline was 61 %, and general follow-up rates until the age of 6 years exceed 80 %. Data collection in mothers, fathers and children include questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome and epigenome wide association screen is available in the participating children. From the age of 5 years, regular detailed hands-on assessments are performed in a dedicated research center including advanced imaging facilities such as Magnetic Resonance Imaging. Eventually, results forthcoming from the Generation R Study contribute to the development of strategies for optimizing health and healthcare for pregnant women and children.

Fetal and infant origins of asthma

Previous studies have suggested that asthma, like other common diseases, has at least part of its origin early in life. Low birth weight has been shown to be associated with increased risks of asthma, chronic obstructive airway disease, and impaired lung function in adults, and increased risks of respiratory symptoms in early childhood. The developmental plasticity hypothesis suggests that the associations between low birth weight and diseases in later life are explained by adaptation mechanisms in fetal life and infancy in response to various adverse exposures. Various pathways leading from adverse fetal and infant exposures to growth adaptations and respiratory health outcomes have been studied, including fetal and early infant growth patterns, maternal smoking and diet, children's diet, respiratory tract infections and acetaminophen use, and genetic susceptibility. Still, the specific adverse exposures in fetal and early postnatal life leading to respiratory disease in adult life are not yet fully understood. Current studies suggest that both environmental and genetic factors in various periods of life, and their epigenetic mechanisms may underlie the complex associations of low birth weight with respiratory disease in later life. New well-designed epidemiological studies are needed to identify the specific underlying mechanisms. This review is focused on specific adverse fetal and infant growth patterns and exposures, genetic susceptibility, possible respiratory adaptations and perspectives for new studies.