Maternal smoking during pregnancy and child overweight: systematic review and meta-analysis

Maternal experiences of racial discrimination and child weight status in the first 3 years of life

Among US racial/ethnic minority women, we examined associations between maternal experiences of racial discrimination and child growth in the first 3 years of life. We analyzed data from Project Viva, a pre-birth cohort study. We restricted analyses to 539 mother–infant pairs; 294 were Black, 127 Hispanic, 110 Asian and 8 from additional racial/ethnic groups. During pregnancy, mothers completed the Experiences of Discrimination survey that measured lifetime experiences of racial discrimination in diverse domains. We categorized responses as 0, 1–2 or ⩾3 domains. Main outcomes were birth weight for gestational age z-score; weight for age (WFA) z-score at 6 months of age; and at 3 years of age, body mass index (BMI) z-score. In multivariable analyses, we adjusted for maternal race/ethnicity, nativity, education, age, pre-pregnancy BMI, household income and child sex and age. Among this cohort of mostly (58.2%) US-born and economically non-impoverished mothers, 33% reported 0 domains of discrimination, 33% reported discrimination in 1–2 domains and 35% reported discrimination in ⩾3 domains. Compared with children whose mothers reported no discrimination, those whose mothers reported ⩾3 domains had lower birth weight for gestational age z-score (β −0.25; 95% CI: −0.45, −0.04), lower 6 month WFA z-score (β −0.34; 95% CI: −0.65, −0.03) and lower 3-year BMI z-score (β −0.33; 95% CI: −0.66, 0.00). In conclusion, we found that among this cohort of US racial/ethnic minority women, mothers’ report of experiencing lifetime discrimination in ⩾ 3 domains was associated with lower fetal growth, weight at 6 months and 3-year BMI among their offspring.

Maternal weight gain during the first half of pregnancy and offspring obesity at 16 years: a prospective cohort study

OBJECTIVE

To assess the association between maternal gestational weight gain (GWG) during the first 20 weeks of gestation and overweight/obesity and abdominal obesity of offspring at the age of 16 years.

DESIGN

A prospective cohort study.

SETTING

The two northernmost provinces of Finland.

POPULATION

Mothers and their adolescent offspring born from singleton pregnancies (3265 boys; 3372 girls) in the Northern Finland Birth Cohort 1986.

METHODS

Maternal weight at 20 weeks of gestation was measured in municipal maternity clinics. Maternal GWG was based on the difference between the measured weight and self-reported pre-pregnancy weight, and was classified into quartiles. Offspring weight, height and waist circumference were measured by study nurses during a clinical examination. Logistic regression analyses [with and without adjustment for maternal pre-pregnancy body mass index (BMI), glucose metabolism, education level, haemoglobin, smoking status, parity, and gender of offspring] were performed.

MAIN OUTCOME MEASURE

Offspring overweight/obesity, based on BMI and abdominal obesity at 16 years.

RESULTS

The highest quartile of maternal weight gain (>7.0 kg during the first 20 weeks of gestation) was independently associated with BMI-based overweight/obesity and abdominal obesity in the 16-year-old offspring (OR 1.46, 95% CI 1.16-1.83, and OR 1.37, 95% CI 1.10-1.72, respectively). Among all covariates, maternal pregravid obesity showed the highest odds for both overweight/obesity and abdominal obesity (OR 4.57, 95% CI 3.18-6.57, and OR 4.43, 95% CI 3.10-6.34, respectively).

CONCLUSIONS

Maternal overnutrition during the first half of gestation predicts offspring overweight/obesity and abdominal obesity in adolescence, yet a high pregravid BMI appears to be a more important determinant of both outcomes.

Role of environmental chemicals in diabetes and obesity: a National Toxicology Program workshop review

BACKGROUND

There has been increasing interest in the concept that exposures to environmental chemicals may be contributing factors to the epidemics of diabetes and obesity. On 11-13 January 2011, the National Institute of Environmental Health Sciences (NIEHS) Division of the National Toxicology Program (NTP) organized a workshop to evaluate the current state of the science on these topics of increasing public health concern.

OBJECTIVE

The main objective of the workshop was to develop recommendations for a research agenda after completing a critical analysis of the literature for humans and experimental animals exposed to certain environmental chemicals. The environmental exposures considered at the workshop were arsenic, persistent organic pollutants, maternal smoking/nicotine, organotins, phthalates, bisphenol A, and pesticides. High-throughput screening data from Toxicology in the 21st Century (Tox21) were also considered as a way to evaluate potential cellular pathways and generate -hypotheses for testing which and how certain chemicals might perturb biological processes related to diabetes and obesity.

CONCLUSIONS

Overall, the review of the existing literature identified linkages between several of the environmental exposures and type 2 diabetes. There was also support for the "developmental obesogen" hypothesis, which suggests that chemical exposures may increase the risk of obesity by altering the differentiation of adipocytes or the development of neural circuits that regulate feeding behavior. The effects may be most apparent when the developmental exposure is combined with consumption of a high-calorie, high-carbohydrate, or high-fat diet later in life. Research on environmental chemical exposures and type 1 diabetes was very limited. This lack of research was considered a critical data gap. In this workshop review, we outline the major themes that emerged from the workshop and discuss activities that NIEHS/NTP is undertaking to address research recommendations. This review also serves as an introduction to an upcoming series of articles that review the literature regarding specific exposures and outcomes in more detail.

Association of childhood obesity with maternal exposure to ambient air polycyclic aromatic hydrocarbons during pregnancy

There are concerns that prenatal exposure to endocrine-disrupting chemicals increases children's risk of obesity. African-American and Hispanic children born in the Bronx or Northern Manhattan, New York (1998-2006), whose mothers underwent personal air monitoring for polycyclic aromatic hydrocarbon (PAH) exposure during pregnancy, were followed up to ages 5 (n = 422) and 7 (n = 341) years. At age 5 years, 21% of the children were obese, as were 25% of those followed to age 7 years. After adjustment for child's sex, age at measurement, ethnicity, and birth weight and maternal receipt of public assistance and prepregnancy obesity, higher prenatal PAH exposures were significantly associated with higher childhood body size. In adjusted analyses, compared with children of mothers in the lowest tertile of PAH exposure, children of mothers in the highest exposure tertile had a 0.39-unit higher body mass index z score (95% confidence interval (CI): 0.08, 0.70) and a relative risk of 1.79 (95% CI: 1.09, 2.96) for obesity at age 5 years, and they had a 0.30-unit higher body mass index z score (95% CI: 0.01, 0.59), a 1.93-unit higher percentage of body fat (95% CI: 0.33, 3.54), and a relative risk of 2.26 (95% CI: 1.28, 4.00) for obesity at age 7 years. The data indicate that prenatal exposure to PAHs is associated with obesity in childhood.

Maternal smoking during pregnancy and offspring trajectories of height and adiposity: comparing maternal and paternal associations

BACKGROUND

Maternal smoking during pregnancy is associated with reduced offspring birth length and has been postulated as a risk factor for obesity. Causality for obesity is not established. Causality is well-supported for birth length, but evidence on persistence of height deficits is inconsistent.

METHODS

We examined the association between maternal smoking during pregnancy and trajectories of offspring height (0-10 years, N = 9424), ponderal index (PI) (0-2 years, N = 9321) and body mass index (BMI) (2-10 years, N = 8887) in the Avon Longitudinal Study of Parents and Children. To strengthen inference, measured confounders were controlled for, maternal and partner smoking associations were compared, dose-response and associations with post-natal smoking were examined.

RESULTS

Maternal smoking during pregnancy was associated with shorter birth length, faster height growth in infancy and slower growth in later childhood. By 10 years, daughters of women who smoke during pregnancy are on average 1.11 cm (SE = 0.27) shorter after adjustment for confounders and partner smoking; the difference is 0.22 cm (SE = 0.22) for partner's smoking. Maternal smoking was associated with lower PI at birth, faster PI increase in infancy, but not with BMI changes 2-10 years. Associations were stronger for maternal than partner smoking for PI at birth and PI changes in infancy, but not for BMI changes after 2 years. A similar dose-response in both maternal and partner smoking was seen for BMI change 2-10 years.

CONCLUSION

Maternal smoking during pregnancy has an intrauterine effect on birth length, and possibly on adiposity at birth and changes in height and adiposity in infancy. We do not find evidence of a specific intrauterine effect on height or adiposity changes after the age of 2 years.

Frequency of under- and overweight among children and adolescents during the economic transition in Poland

The aim of this study is to examine the prevalence of underweight, overweight and obesity, using International Obesity Task Force (IOTF) criteria, in four cohorts of children and adolescents living in Poland in different economic eras: communist economy (1977/1978), crisis of the 1980s (1987/1988), political and economic transformation (1992/1994) and the free market economy (2002/2004). Analysis was conducted on a database including 10,934 records for children of the age 7-18 years. In Poland, in the last 26 years of economic and political transformations, the epidemic of obesity was not noticed but the growing incidence of children and adolescents with body mass deficit was observed (p<0.0001) (20.2% of girls in 2002/2004 vs. 11.0% in 1977/1978 and 12.1% of boys in 2002/2004 vs. 7.2% in 1977/1978). Lower parental education and a higher number of children in a family resulted in a higher prevalence of underweight (odds ratio [OR] fluctuated from 1.26 to 1.63). The social effects of the political transformation in Poland significantly affected families with low socio-economic status (SES), and especially more eco-sensitive boys. This result is opposite to the trends observed in Western countries and makes an important contribution to the current knowledge of the course of further changes in weight-to-height ratio at a global scale.

Need for early interventions in the prevention of pediatric overweight: a review and upcoming directions

Childhood obesity is currently one of the most prevailing and challenging public health issues among industrialized countries and of international priority. The global prevalence of obesity poses such a serious concern that the World Health Organization (WHO) has described it as a "global epidemic." Recent literature suggests that the genesis of the problem occurs in the first years of life as feeding patterns, dietary habits, and parental feeding practices are established. Obesity prevention evidence points to specific dietary factors, such as the promotion of breastfeeding and appropriate introduction of nutritious complementary foods, but also calls for attention to parental feeding practices, awareness of appropriate responses to infant hunger and satiety cues, physical activity/inactivity behaviors, infant sleep duration, and family meals. Interventions that begin at birth, targeting multiple factors related to healthy growth, have not been adequately studied. Due to the overwhelming importance and global significance of excess weight within pediatric populations, this narrative review was undertaken to summarize factors associated with overweight and obesity among infants and toddlers, with focus on potentially modifiable risk factors beginning at birth, and to address the need for early intervention prevention.

Developmental cigarette smoke exposure: kidney proteome profile alterations in low birth weight pups

The Brenner hypothesis states that a congenital reduction in nephron number predisposes to adult-onset hypertension and renal failure. The reduction in nephron number induced by proportionally smaller kidney mass may predispose offspring to glomerular hyperfiltration with maturity onset obesity. Developmental cigarette smoke exposure (CSE) results in intrauterine growth retardation with a predisposition to obesity and cardiovascular disease at maturity. Utilizing a mouse model of 'active' developmental CSE (gestational day [GD] 1-postnatal day [PD] 21; cotinine>50 ng/mL) characterized by persistently smaller offspring with proportionally decreased kidney mass, the present study examined the impact of developmental CSE on the abundance of proteins associated with cellular metabolism in the kidney. Following cessation of CSE on PD21, kidney tissue was collected from CSE and Sham exposed pups for 2D-SDS-PAGE based proteome profiling with statistical analysis by partial least squares-discriminant analysis (PLS-DA) with affected molecular pathways identified by ingenuity pathway analysis. Proteins whose expression in the kidney were affected by developmental CSE belonged to the inflammatory disease, cell to cell signaling/interaction, lipid metabolism, small molecule biochemistry, cell cycle, respiratory disease, nucleic acid and carbohydrate metabolism networks. The present findings indicate that developmental CSE alters the kidney proteome. The companion paper details the liver proteome alterations in the same offspring.

Early markers of adult obesity: a review

The purpose of this review was to evaluate factors in early childhood (≤5 years of age) that are the most significant predictors of the development of obesity in adulthood. Factors of interest included exposures/insults in the prenatal period, infancy and early childhood, as well as other socio-demographic variables such as socioeconomic status (SES) or birth place that could impact all three time periods. An extensive electronic and systematic search initially resulted in 8,880 citations, after duplicates were removed. Specific inclusion and exclusion criteria were set, and following two screening processes, 135 studies were retained for detailed abstraction and analysis. A total of 42 variables were associated with obesity in adulthood; however, of these, only seven variables may be considered as potential early markers of obesity based on the reported associations. Possible early markers of obesity included maternal smoking and maternal weight gain during pregnancy. Probable early markers of obesity included maternal body mass index, childhood growth patterns (early rapid growth and early adiposity rebound), childhood obesity and father's employment (a proxy measure for SES in many studies). Health promotion programmes/agencies should consider these factors as reasonable targets to reduce the risk of adult obesity.

Maternal inflammatory bowel disease and offspring body size: a prospective cohort study

BACKGROUND

Maternal inflammatory bowel disease (IBD) may influence intrauterine growth and hence size at birth, but the consequences for offspring in later life remain uncertain. This study investigated the growth of children of mothers with Crohn's disease (CD) or ulcerative colitis (UC).

METHODS

The Danish National Birth Cohort, comprising 40,640 mother-child pairs with 7-year follow-up of children's height and weight, were linked to the Danish National Disease Register, whereby 50 mothers with CD and 147 mothers with UC were identified. Associations were tested by regression analyses, taking several covariates into account.

RESULTS

Children of mothers with IBD were significantly shorter at birth than children of unaffected mothers (adjusted; CD, difference in cm, -0.82; 95% confidence interval [CI], -1.39 to -0.25; UC, -0.41; 95% CI, -0.75 to -0.07) and they tended to be of lower birth weight (adjusted; CD, difference in grams, -119.7; 95% CI, -246.7 to 7.3; UC, -64.0; 95% CI, -138.7 to 10.7). However, during the first year of life children of IBD mothers reached similar body sizes as children of unaffected mothers. At the 7-year follow-up, girls, but not boys, of CD mothers tended to be overweight (adjusted odds ratio [OR], 2.47; 95% CI, 0.98-6.24) and had increased waist circumference (adjusted difference in cm, 3.48; 95% CI, 1.40-5.58) compared to the unaffected population.

CONCLUSIONS

The present study confirms that maternal history of IBD leads to decreased birth size in offspring. Reassuringly, body size in children of IBD mothers approached body size in children of unaffected mothers during childhood.

Is low birth weight associated with adiposity in contemporary U.S. youth? The Exploring Perinatal Outcomes among Children (EPOCH) Study

Little is known about the relationship between low birth weight (BW), as a marker of under-nutrition in utero, and childhood body mass index (BMI) and adiposity parameters, including skinfold thickness, abdominal subcutaneous (SAT) and visceral adipose tissues (VAT) and intramyocellular accumulation of lipids (IMCL). The EPOCH Study (Exploring Perinatal Outcomes among Children) explored the association between BW and markers of adiposity in contemporary, multi-ethnic children from Colorado. A total of 442 youth age 6-13 years (50% male, mean age 10.5 years) had anthropometric measurements, abdominal SAT and VAT measured by magnetic resonance imaging and IMCL deposition in the soleus muscle measured by nuclear magnetic resonance spectroscopy. BW and gestational age were ascertained from an electronic perinatal database. A weak positive association between BW and current BMI (P=0.05) was seen, independent of demographic, perinatal, socio-economic and current lifestyle factors. When adjusted for current BMI, every one standard deviation decrease in BW (~500 g), was associated with a 8.8 cm(2) increase in SAT, independent of potential confounders. In conclusion, in a contemporary cohort of youth, BW was positively, but weakly, associated with BMI and inversely, though weakly, associated with SAT, independent of current BMI. There were no significant associations between BW and waist circumference, skinfolds, VAT and IMCL. Our results provide some support to the hypothesis that under-nutrition in utero, as reflected by lower BW, is associated with lower overall childhood body size, but an increased propensity for abdominal adiposity, reflected in this young age-group, predominantly as subcutaneous fat.

In utero exposure to maternal tobacco smoke and subsequent obesity, hypertension, and gestational diabetes among women in the MoBa cohort

BACKGROUND

Environmental factors influencing the developmental origins of health and disease need to be identified and investigated. In utero exposure to tobacco smoke has been associated with obesity and a small increase in blood pressure in children; however, whether there is a corresponding increased risk of conditions such as diabetes and hypertension during adulthood remains unclear.

OBJECTIVE

Our goal was to assess the association of self-reported in utero exposure to tobacco smoke with the prevalence of obesity, hypertension, type 2 diabetes mellitus (T2DM), and gestational diabetes mellitus (GDM) in women 14-47 years of age.

METHODS

We conducted a cross-sectional analysis of the Norwegian Mother and Child Cohort Study, which enrolled pregnant women in Norway from 1999 thorough 2008. Exposure to tobacco smoke in utero (yes vs. no) was ascertained on the baseline questionnaire (obtained at ~ 17 weeks' gestation); the outcomes were ascertained from the Medical Birth Registry of Norway and the questionnaire. Our analysis included 74,023 women.

RESULTS

Women exposed to tobacco smoke in utero had 1.53 times the odds of obesity [95% confidence interval (CI): 1.45, 1.61] relative to those unexposed, after adjusting for age, education, and personal smoking. After further adjustment for body mass index, the odds ratio for hypertension was 1.68 (95% CI: 1.19, 2.39); for T2DM 1.14 (95% CI: 0.79, 1.65); and for GDM 1.32 (95% CI: 1.10, 1.58) among exposed compared with unexposed.

CONCLUSIONS

Exposure to tobacco smoke in utero was associated with obesity, hypertension, and GDM in adult women. The possibility that the associations were attributable to unmeasured confounding cannot be excluded.

Prenatal exposure to cigarette smoke or alcohol and cerebellum volume in attention-deficit/hyperactivity disorder and typical development

Prenatal exposure to teratogenic substances, such as nicotine or alcohol, increases the risk of developing attention-deficit/hyperactivity disorder (ADHD). To date, studies examining this relationship have used symptom scales as outcome measures to assess the effect of prenatal exposure, and have not investigated the neurobiological pathways involved. This study explores the effect of prenatal exposure to cigarettes or alcohol on brain volume in children with ADHD and typically developing controls. Children with ADHD who had been exposed prenatally to either substance were individually matched to children with and without ADHD who had not been. Controls who had been exposed prenatally were also individually matched to controls who had not been. For prenatal exposure to both smoking and alcohol, we found a pattern where subjects with ADHD who had been exposed had the smallest brain volumes and unexposed controls had the largest, with intermediate volumes for unexposed subjects with ADHD. This effect was most pronounced for cerebellum. A similar reduction fell short of significance for controls who had been exposed to cigarettes, but not alcohol. Our results are consistent with an additive effect of prenatal exposure and ADHD on brain volume, with the effects most pronounced for cerebellum.

Lifecourse approach to racial/ethnic disparities in childhood obesity

Eliminating racial/ethnic disparities in health and health care is a national priority, and obesity is a prime target. During the last 30 y in the United States, the prevalence of obesity among children has dramatically increased, sparing no age group. Obesity in childhood is associated with adverse cardio-metabolic outcomes such as hypertension, hyperlipidemia, and type II diabetes and with other long-term adverse outcomes, including both physical and psychosocial consequences. By the preschool years, racial/ethnic disparities in obesity prevalence are already present, suggesting that disparities in childhood obesity prevalence have their origins in the earliest stages of life. Several risk factors during pregnancy are associated with increased risk of offspring obesity, including excessive maternal gestational weight gain, gestational diabetes, smoking during pregnancy, antenatal depression, and biological stress. During infancy and early childhood, rapid infant weight gain, infant feeding practices, sleep duration, child's diet, physical activity, and sedentary practices are associated with the development of obesity. Studies have found substantial racial/ethnic differences in many of these early life risk factors for childhood obesity. It is possible that racial/ethnic differences in early life risk factors for obesity might contribute to the high prevalence of obesity among minority preschool-age children and beyond. Understanding these differences may help inform the design of clinical and public health interventions and policies to reduce the prevalence of childhood obesity and eliminate disparities among racial/ethnic minority children.

Impact of maternal physical activity and infant feeding practices on infant weight gain and adiposity

Increasing evidence supports the contribution of intrauterine environmental exposures on obesity risk in offspring. Few studies have included maternal and infant lifestyle factors. Our objective was to study the impact of maternal physical activity, infant feeding, and screen time on offspring weight gain and adiposity. In a prospective cohort study, 246 mothers underwent testing during pregnancy to assess glucose tolerance status and insulin sensitivity. Anthropometry and questionnaires on physical activity, infant feeding, and screen time were completed. Multiple-linear regression was performed to examine the impact of maternal and infant factors on infant weight gain and weight-for-length z-score at 1 year. Infant weight outcomes were negatively predicted by maternal pregravid vigorous/sport index and exclusive breastfeeding duration. After adjustment, each unit increase in maternal pregravid vigorous/sport index decreased infant weight gain by 218.6 g (t = 2.44, P = 0.016) and weight-for-length z-score by 0.20 (t = 2.17, P = 0.031). Each month of exclusive breastfeeding reduced infant weight gain by 116.4 g (t = 3.97, P < 0.001) and weight-for-length z-score by 0.08 (t = 2.59, P = 0.01). Maternal pregravid physical activity and exclusive breastfeeding duration are associated with weight gain and adiposity as early as 1 year of age.

Socio-economic, familial and perinatal factors associated with obesity in Sydney schoolchildren

AIM

To examine associations between socio-economic, familial and perinatal factors with overweight/obesity in 6- and 12-year-old schoolchildren.

METHODS

Eligible year-1 (1765/2238, mean age 6.7 years) and year-7 students (2353/3144, mean age, 12.7 years) from a random cluster sample of 55 Sydney schools were examined during 2003-2005. Height, weight and body mass index were measured. Overweight or obesity was classified using International Obesity Task Force cut points. Information about each child's socio-demographic status, familial and perinatal information was sought in parental questionnaires.

RESULTS

After multivariate adjustment, lower parental education was significantly associated with prevalent overweight and obesity in 6-year-old children, odds ratio (OR) 1.52 (95% confidence interval (CI) 1.15-2.01) and OR 2.16 (CI 1.34-4.13), respectively. Smoking during pregnancy was associated with a higher likelihood of being obese among both 6- and 12-year-old children, OR 1.90 (CI 1.05-3.46) and OR 1.78 (CI 1.22-2.61). Population attributable risk estimates indicate that 14.9% and 10.1% of prevalent cases of obesity in 12-year-old children may be attributable to being: an only child or a heavy newborn, respectively.

CONCLUSIONS

We show interdependent relationships between socio-economic, familial and perinatal factors and childhood weight status. Improved understanding of these pathways may help in developing childhood obesity prevention strategies.

[The Fetal Tobacco Syndrome - A statement of the Austrian Societies for General- and Family Medicine (ÖGAM), Gynecology and Obstetrics (ÖGGG), Hygiene, Microbiology and Preventive Medicine (ÖGHMP), Pediatrics and Adolescence Medicine (ÖGKJ) as well as Pneumology (ÖGP)]

Over more than 50 years, the nocuous effects of smoking in pregnancy on the fetus are well known. In the first years of science the focus was primarily on restricted fetal growth while in more recent years over 10.000 studies investigated the incomparably big sum of detrimental effects for the unborn's health. In this statement we want to present the recent scientific findings on this topic. The statement is aimed to show all doctors who treat pregnant women the present situation and evidence. In the beginning we give a short overview about the epidemiological situation in Europe. Then we present step by step the health effects with regards to pathophysiology and clinics. Furthermore the reader will learn about possibilities for smoking cessation in pregnancy. The problem of passive-smoking in pregnancy will be dealt with in a separate chapter. At present there is strong evidence that pregnant smoking has a detrimental effect on birth-weight, placenta-associated disease, stillbirth, sudden infant death syndrome (SIDS), childhood overweight, clefts, lung function, asthma, cardiovascular diseases and mental developmental disorders. These factors can be summarized by the term Fetal Tobacco Syndrome. There is supply for more studies for less investigated health effects. Pregnancy is a chance to stop smoking as most women show a high motivation in this period. Hence doctors of all disciplines should inform pregnant women about the detrimental effects of smoking on their unborn child and show them possibilities for smoking cessation.

Early markers of adult obesity: a review

The purpose of this review was to evaluate factors in early childhood (≤5 years of age) that are the most significant predictors of the development of obesity in adulthood. Factors of interest included exposures/insults in the prenatal period, infancy and early childhood, as well as other socio-demographic variables such as socioeconomic status (SES) or birth place that could impact all three time periods. An extensive electronic and systematic search initially resulted in 8,880 citations, after duplicates were removed. Specific inclusion and exclusion criteria were set, and following two screening processes, 135 studies were retained for detailed abstraction and analysis. A total of 42 variables were associated with obesity in adulthood; however, of these, only seven variables may be considered as potential early markers of obesity based on the reported associations. Possible early markers of obesity included maternal smoking and maternal weight gain during pregnancy. Probable early markers of obesity included maternal body mass index, childhood growth patterns (early rapid growth and early adiposity rebound), childhood obesity and father's employment (a proxy measure for SES in many studies). Health promotion programmes/agencies should consider these factors as reasonable targets to reduce the risk of adult obesity.

Identifying infants at risk of becoming obese: can we and should we?

OBJECTIVES

Increased understanding of the risk factors for childhood obesity has raised the possibility of identifying infants who are at risk of becoming overweight or obese, enabling early intervention for infants at high risk. This paper considers the known risk factors, describes statistical work aimed at identifying risk, and considers the ethical and practical issues of such a development.

STUDY DESIGN AND METHODS

An overview of the published evidence for risk factors in the early development of overweight and obesity, and a statistical assessment of the practicality of developing a simple obesity risk assessment tool (ORT) for use in the primary care setting.

RESULTS

Analysis of data from two currently available UK birth cohort studies suggests that an ORT based on these data does not provide acceptable levels of specificity and sensitivity for use in a primary care setting.

CONCLUSION

Further development of an ORT using additional data and enhanced statistical analysis may lead to a practical tool. However the practical, ethical and legal issues involved in its use, and the public health policy considerations that follow must be resolved.

Effects of maternal smoking during pregnancy on body composition in offspring

BACKGROUND

The aim of the present cross-sectional study was to use objective methods to assess the association between maternal smoking and body composition in offspring.

METHODS

A total of 2508 grade 4 school children were enrolled; all underwent lifestyle disease and passive smoking screening. Children were classified into four groups according to their urinary cotinine level and maternal smoking status during or before pregnancy. Items measured on lifestyle disease screening were compared among the four groups.

RESULTS

Only degree of obesity (DO) and body mass index (BMI) were significantly associated with maternal smoking during pregnancy. The prevalence of both DO >20% and DO >30%, and BMI >22% and BMI >25% was highest in children of mothers who smoked during pregnancy. These children had a tendency toward shorter height and increased weight although it was not statistically significant. There were no significant differences between maternal smoking status and lipid profile among groups. Confounders such as food, exercise and sleep were able to be eliminated.

CONCLUSION

Maternal smoking during pregnancy may be an independent risk factor of changing body composition in offspring, that is, shorter height and increased weight.

Tobacco smoke exposure before, during, and after pregnancy and risk of overweight at age 6

Maternal smoking during pregnancy has been associated with overweight and obesity in childhood and is strongly correlated with children's tobacco smoke exposure before and after pregnancy. We investigated the independent association of tobacco smoke exposure at various pre- and postnatal periods and overweight at age 6. A total of 1,954 children attending the 2001-2002 school entrance health examination in the city of Aachen, Germany, were included into this study. Height and weight were measured, BMI was calculated. Tobacco smoke exposure at various periods, other lifestyle and sociodemographic factors were ascertained by questionnaire. Multiple logistic regression models were used to assess the association between tobacco smoke exposure and overweight. Prevalence of overweight was 8.9%. Significant positive associations were found with maternal smoking before and during pregnancy and during the first and sixth year of life. When all smoking periods were included into one logistic model simultaneously, secondhand smoke exposure after birth remained positively associated with overweight at age 6 at either one of the two time periods (first year only: odds ratio (OR) (95% confidence interval (CI)): 2.94 (1.30-6.67), sixth year only: 2.57 (1.64-4.04), respectively) or at both (4.43 (2.24-8.76)). Exposure to tobacco smoke during the first years of life appears to be a key risk factor for development of childhood overweight.

Maternal cigarette smoke exposure contributes to glucose intolerance and decreased brain insulin action in mice offspring independent of maternal diet

BACKGROUND

Maternal smoking leads to intrauterine undernutrition and is associated with low birthweight and higher risk of offspring obesity. Intrauterine smoke exposure (SE) may alter neuroendocrine mediators regulating energy homeostasis as chemicals in cigarette smoke can reach the fetus. Maternal high-fat diet (HFD) consumption causes fetal overnutrition; however, combined effects of HFD and SE are unknown. Thus we investigated the impact of combined maternal HFD and SE on adiposity and energy metabolism in offspring.

METHOD

Female Balb/c mice had SE (2 cigarettes/day, 5 days/week) or were sham exposed for 5 weeks before mating. Half of each group was fed HFD (33% fat) versus chow as control. The same treatment continued throughout gestation and lactation. Female offspring were fed chow after weaning and sacrificed at 12 weeks.

RESULTS

Birthweights were similar across maternal groups. Faster growth was evident in pups from SE and/or HFD dams before weaning. At 12 weeks, offspring from HFD-fed dams were significantly heavier than those from chow-fed dams (chow-sham 17.6±0.3 g; chow-SE 17.8±0.2 g; HFD-sham 18.7±0.3 g; HFD-SE 18.8±0.4 g, P<0.05 maternal diet effect); fat mass was significantly greater in offspring from chow+SE, HFD+SE and HFD+sham dams. Both maternal HFD and SE affected brain lactate transport. Glucose intolerance and impaired brain response to insulin were observed in SE offspring, and this was aggravated by maternal HFD consumption.

CONCLUSION

While maternal HFD led to increased body weight in offspring, maternal SE independently programmed adverse health outcomes in offspring. A smoke free environment and healthy diet during pregnancy is desirable to optimize offspring health.

Cardiovascular and metabolic influences of fetal smoke exposure

Many epidemiological studies showed associations of low birth weight with cardiovascular disease, type 2 diabetes and obesity. The associations seem to be consistent and stronger among subjects with a postnatal catch up growth. It has been suggested that developmental changes in response to adverse fetal exposures might lead to changes in the fetal anatomy and physiology. These adaptations may be beneficial for short term, but may lead to common diseases in adulthood. Maternal smoking during pregnancy is one of the most important adverse fetal exposures in Western countries, and is known to be associated with a 150-200 g lower birth weight. An accumulating body of evidence suggests that maternal smoking during pregnancy might be involved in pathways leading to both low birth weight and common diseases, including cardiovascular disease, type 2 diabetes and obesity, in adulthood. In this review, we discuss epidemiological studies focused on the associations of maternal smoking with fetal growth and development and cardiovascular and metabolic disease in later life. We also discuss potential biological mechanisms, and challenges for future epidemiological studies.

Cardiovascular and metabolic influences of fetal smoke exposure

Many epidemiological studies showed associations of low birth weight with cardiovascular disease, type 2 diabetes and obesity. The associations seem to be consistent and stronger among subjects with a postnatal catch up growth. It has been suggested that developmental changes in response to adverse fetal exposures might lead to changes in the fetal anatomy and physiology. These adaptations may be beneficial for short term, but may lead to common diseases in adulthood. Maternal smoking during pregnancy is one of the most important adverse fetal exposures in Western countries, and is known to be associated with a 150–200 g lower birth weight. An accumulating body of evidence suggests that maternal smoking during pregnancy might be involved in pathways leading to both low birth weight and common diseases, including cardiovascular disease, type 2 diabetes and obesity, in adulthood. In this review, we discuss epidemiological studies focused on the associations of maternal smoking with fetal growth and development and cardiovascular and metabolic disease in later life. We also discuss potential biological mechanisms, and challenges for future epidemiological studies.

Lower birth weight and increased body fat at school age in children prenatally exposed to modern pesticides: a prospective study

BACKGROUND

Endocrine disrupting chemicals have been hypothesized to play a role in the obesity epidemic. Long-term effects of prenatal exposure to non-persistent pesticides on body composition have so far not been investigated. The purpose of this study was to assess possible effects of prenatal exposure to currently used pesticides on children's growth, endocrine and reproductive function.

METHODS

In a prospective study of 247 children born by women working in greenhouses in early pregnancy, 168 were categorized as prenatally exposed to pesticides. At three months (n = 203) and at 6 to 11 years of age (n = 177) the children underwent a clinical examination and blood sampling for analysis of IGF-I, IGFBP3 and thyroid hormones. Body fat percentage at age 6 to 11 years was calculated from skin fold measurements. Pesticide related associations were tested by linear multiple regression analysis, adjusting for relevant confounders.

RESULTS

Compared to unexposed children birth weight and weight for gestational age were lower in the highly exposed children: -173 g (-322; -23), -4.8% (-9.0; -0.7) and medium exposed children: -139 g (-272; -6), -3.6% (-7.2; -0.0). Exposed (medium and highly together) children had significantly larger increase in BMI Z-score (0.55 SD (95% CI: 0.1; 1.0) from birth to school age) and highly exposed children had 15.8% (0.2; 34.6) larger skin folds and higher body fat percentage compared to unexposed. If prenatally exposed to both pesticides and maternal smoking (any amount), the sum of four skin folds was 46.9% (95% CI: 8.1; 99.5) and body fat percentage 29.1% (95% CI: 3.0; 61.4) higher. There were subtle associations between exposure and TSH Z-score -0.66(-1.287; -0.022) and IGF-I Z-score (girls: -0.62(-1.0; -0.22), boys: 0.38(-0.03; 0.79)), but not IGFBP3.

CONCLUSIONS

Occupational exposure to currently used pesticides may have adverse effects in spite of the added protection offered to pregnant women. Maternal exposure to combinations of modern, non-persistent pesticides during early pregnancy was associated with affected growth, both prenatally and postnatally. We found a biphasic association with lower weight at birth followed by increased body fat accumulation from birth to school age. We cannot rule out some residual confounding due to differences in social class, although this was adjusted for. Associations were stronger in highly exposed than in medium exposed children, and effects on body fat content at school age was potentiated by maternal smoking in pregnancy.

Obesity in rural youth: looking beyond nutrition and physical activity

Contributors to excessive obesity in rural youth include well-documented nutrition and physical activity behaviors. However, emerging research suggests that preventing excessive weight gain and smoking during pregnancy, teen pregnancy, and child abuse also could reduce obesity in this vulnerable population. These traditional and emerging, nontraditional factors need to be addressed within the confines of current challenges faced by rural communities. An enhanced ecological model provides a framework for combining traditional and nontraditional factors into a more comprehensive approach that addresses the complexity of the issues contributing to youth obesity.

Asthma and obesity in three-year-old urban children: role of sex and home environment

OBJECTIVE

To examine whether the relationship between obesity and asthma in young girls and boys can be explained by social and physical characteristics of the home environment.

STUDY DESIGN

We examined the relationship between asthma and obesity in children in the Fragile Families and Child Wellbeing Study (n=1815). Asthma was determined through maternal report of asthma diagnosis by a doctor (active in past 12 months). Weight and height of child was measured during an in-home visit. Data on home social (maternal depression, intimate partner violence) and physical environmental factors (housing quality, tobacco exposure) were collected via questionnaire.

RESULTS

Ten percent of children had active asthma, 19% of children were overweight, and 17% of children were obese. In fully adjusted models, obese children had twice the odds of having asthma (OR, 2.3; 95% CI, 1.5-3.3) compared with children of normal body weight. In stratified analyses, overweight boys, but not overweight girls, had increased of odds of asthma. Obese boys and girls had increased odds of asthma compared with boys and girls of normal body weight.

CONCLUSION

The relationship between asthma and obesity is present in boys and girls as young as 3 years of age; a relationship between being overweight and asthma is only present among boys. This relationship is not attributable to shared social and environmental factors of the children's home.

Evidence for the intra-uterine programming of adiposity in later life

AIM

Research in animals has shown that altering foetal nutrition by under-nourishing or over-nourishing the mother or rendering her diabetic or foetal exposure to glucocorticoids and toxins can programme obesity in later life. The increased adiposity is mediated by permanent changes in appetite, food choices, physical activity and energy metabolism. In humans, increased adiposity has been shown in people who experienced foetal under-nutrition due to maternal famine or over-nutrition due to maternal diabetes. Lower birth weight (a proxy for foetal under-nutrition) is associated with a reduced adult lean mass and increased intra-abdominal fat. Higher birth-weight caused by maternal diabetes is associated with increased total fat mass and obesity in later life. There is growing evidence that maternal obesity, without diabetes, is also a risk factor for obesity in the child, due to foetal over-nutrition effects. Maternal smoking is associated with an increased risk of obesity in the children, although a causal link has not been proven. Other foetal exposures associated with increased adiposity in animals include glucocorticoids and endocrine disruptors.

CONCLUSIONS

Reversing the current obesity epidemic will require greater attention to, and better understanding of, these inter-generational (mother-offspring) factors that programme body composition during early development.

Parental smoking during pregnancy, early growth, and risk of obesity in preschool children: the Generation R Study

BACKGROUND

Maternal smoking during pregnancy seems to be associated with obesity in offspring. Not much is known about the specific critical exposure periods or underlying mechanisms for this association.

OBJECTIVE

We assessed the associations of active maternal and paternal smoking during pregnancy with early growth characteristics and risks of overweight and obesity in preschool children.

DESIGN

This study was a population-based, prospective cohort study from early fetal life until the age of 4 y in 5342 mothers and fathers and their children. Growth characteristics [head circumference, length, weight, and body mass index (BMI; in kg/m(2))] and overweight and obesity were repeatedly measured at the ages of 1, 2, 3, and 4 y.

RESULTS

In comparison with children from nonsmoking mothers, children from mothers who continued smoking during pregnancy had persistently smaller head circumferences and heights until the age of 4 y, whereas their weights were lower only until the age of 3 mo. This smaller length and normal to higher weight led to an increased BMI [SD score difference: 0.11; 95% CI: 0.02, 0.20; P < 0.05)] and an increased risk of obesity (odds ratio: 1.61; 95% CI: 1.03, 2.53; P < 0.05) at the age of 4 y. In nonsmoking mothers, paternal smoking was not associated with postnatal growth characteristics or risk of obesity in offspring. Maternal smoking during pregnancy was associated with a higher BMI at the age of 4 y in children with a normal birth weight and in those who were small for gestational age at birth.

CONCLUSION

Our findings suggest that direct intrauterine exposure to smoke until late pregnancy leads to different height and weight growth adaptations and increased risks of overweight and obesity in preschool children.

Maternal smoking during pregnancy and offspring growth in childhood: 1993 and 2004 Pelotas cohort studies

OBJECTIVE

To explore the effects of maternal smoking during pregnancy on offspring growth using three approaches: (1) multiple adjustments for socioeconomic and parental factors, (2) maternal-paternal comparisons as a test of putative intrauterine effects and (3) comparisons between two birth cohort studies.

METHODS

Population-based birth cohort studies were carried out in Pelotas, Brazil, in 1993 and 2004. Cohort members were followed up at 3, 12, 24 and 48 months. Multiple linear regression analysis was used to examine the relationships between maternal and paternal prenatal smoking and offspring anthropometric indices. In the 2004 cohort, the association of smoking with trunk length, leg length and leg-to-sitting-height ratio at 48 months was also explored.

RESULTS

Maternal smoking during pregnancy was associated with reduced z scores of length/height-for-age at each follow-up in both cohorts and reduced leg length at 48 months in the 2004 cohort. Children older than 3 months born to smoking women showed a higher body mass index-for-age z score than children of non-smoking women.

CONCLUSIONS

The results of this study strongly support the hypothesis that maternal smoking during pregnancy impairs linear growth and promotes overweight in childhood.

Intestinal microflora and body mass index during the first three years of life: an observational study

Background

Recent research on obesity has demonstrated that the intestinal microflora can have an important influence on host energy balance. The aim of the study was to investigate the relationship between the intestinal microflora and the body mass index in the first 3 years of life.

Results

In a prospective study, a faecal sample from 138 infants was taken at the age of 3, 26 and 52 weeks and cultured on selective media for 6 bacterial genera. Between the age of 1 and 3 years the Body Mass Index Standard Deviation Score (BMI SDS) of these children was determined. The association between the intestinal flora and BMI SDS was assessed for each bacterial genus. A positive correlation was found between the Bacteroides fragilis concentration and the BMI SDS at the age of 3 and 26 weeks. The Staphylococcus concentration showed a negative correlation with the BMI SDS at the age of 3 and 52 weeks. A low intestinal ratio of Staphylococcus/Bacteroides fragilis at the age of 3 weeks, corresponding to a low Staphylococcus and a high Bacteroides fragilis concentration, was associated with a higher BMI SDS during the first three years of life.

Conclusion

High intestinal Bacteroides fragilis and low Staphylococcus concentrations in infants between the age of 3 weeks and 1 year were associated with a higher risk of obesity later in life. This study could provide new targets for a better and more effective modulation of the intestinal microflora in infants.

Childhood overweight after establishment of the gut microbiota: the role of delivery mode, pre-pregnancy weight and early administration of antibiotics

OBJECTIVE

To investigate whether delivery mode (vaginal versus by caesarean section), maternal pre-pregnancy body mass index (BMI) and early exposure to antibiotics (<6 months of age) influence child's risk of overweight at age 7 years, hence supporting the hypotheses that environmental factors influencing the establishment and diversity of the gut microbiota are associated with later risk of overweight.

DESIGN

Longitudinal, prospective study with measure of exposures in infancy and follow-up at age 7 years.

METHODS

A total of 28 354 mother-child dyads from the Danish National Birth Cohort, with information on maternal pre-pregnancy BMI, delivery mode and antibiotic administration in infancy, were assessed. Logistic regression analyses were performed with childhood height and weight at the 7-year follow-up as outcome measures.

RESULTS

Delivery mode was not significantly associated with childhood overweight (odds ratio (OR):1.18, 95% confidence interval (CI): 0.95-1.47). Antibiotics during the first 6 months of life led to increased risk of overweight among children of normal weight mothers (OR: 1.54, 95% CI: 1.09-2.17) and a decreased risk of overweight among children of overweight mothers (OR: 0.54, 95% CI: 0.30-0.98). The same tendency was observed among children of obese mothers (OR: 0.85, 95% CI: 0.41-1.76).

CONCLUSION

The present cohort study revealed that a combination of early exposures, including delivery mode, maternal pre-pregnancy BMI and antibiotics in infancy, influences the risk of overweight in later childhood. This effect may potentially be explained by an impact on establishment and diversity of the microbiota.

Modulation of cell adhesion systems by prenatal nicotine exposure in limbic brain regions of adolescent female rats

Maternal smoking during pregnancy (MS) has long-lasting neurobehavioural effects on the offspring. Many MS-associated psychiatric disorders begin or change symptomatology during adolescence, a period of continuous development of the central nervous system. However, the underlying molecular mechanisms are largely unknown. Given that cell adhesion molecules (CAMs) modulate various neurotransmitter systems and are associated with many psychiatric disorders, we hypothesize that CAMs are altered by prenatal treatment of nicotine, the major psychoactive component in tobacco, in adolescent brains. Pregnant Sprague-Dawley rats were treated with nicotine (3 mg/kg.d) or saline via osmotic mini-pumps from gestational days 4 to 18. Female offspring at postnatal day 35 were sacrificed, and several limbic brain regions (the caudate putamen, nucleus accumbens, prefrontal cortex, and amygdala) were dissected for evaluation of gene expression using microarray and quantitative RT-PCR techniques. Various CAMs including neurexin, immunoglobulin, cadherin, and adhesion-GPCR superfamilies, and their intracellular signalling pathways were modified by gestational nicotine treatment (GN). Among the CAM-related pathways, GN has stronger effects on cytoskeleton reorganization pathways than on gene transcription pathways. These effects were highly region dependent, with the caudate putamen showing the greatest vulnerability. Given the important roles of CAMs in neuronal development and synaptic plasticity, our findings suggest that alteration of CAMs contributes to the neurobehavioural deficits associated with MS. Further, our study underscores that low doses of nicotine produce substantial and long-lasting changes in the brain, implying that nicotine replacement therapy during pregnancy may carry many of the same risks to the offspring as MS.

Being too large for gestational age precedes childhood obesity in African Americans

OBJECTIVE

The purpose of this study was to investigate the association between large-for-gestational-age (LGA) infants and the development of childhood obesity in an inner-city primarily African American population.

STUDY DESIGN

Maternal, neonatal, socioeconomic, and nutritional histories were collected for mothers with children who were 2-5 years old. Associations between Alexander and customized birthweight percentiles and body mass index for the age of the child were examined.

RESULTS

One hundred ninety-five mother-child pairs were enrolled; the childhood obesity rate was 18%. Increasing Alexander and customized birthweight percentiles were related to increasing obesity. LGA newborn infants were 2.5 times more likely to be obese in childhood than average size newborn infants. Maternal smoking was also associated with childhood obesity.

CONCLUSION

LGA infants have the highest likelihood of childhood obesity in this inner-city predominantly African American population. Customized growth percentiles perform best in the identification of the highest risk population.

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

A number of cross-sectional and prospective studies suggested a priming effect of maternal smoking in pregnancy on offspring's obesity. It has been hypothesized that this association might be explained by low birth weight and subsequent catch-up growth in the causal pathway. We therefore examined the role of birth weight in children exposed versus not exposed to cigarette smoking in utero on later body mass index (BMI). Using data of 12,383 children and adolescents (3-17 years of age) recorded in a German population-based survey (KiGGS), we assessed mean body mass index standard deviation scores (BMI-SDS) in different birth weight SDS categories, stratified for children with smoking and non-smoking mothers. We calculated spline regression models with BMI-SDS as outcome variable, cubic splines of birth weight SDS, and potential confounding factors. Children whose mothers had been smoking during pregnancy had lower birth weight SDS and higher BMI-SDS at interview compared to children of non-smoking mothers. However, we observed a linear association between birth weight SDS and BMI-SDS in crude analyses for both groups. Similarly, almost linear effects were observed in adjusted spline regression analyses, except for children with very low birth weight. The respective 95% confidence bands did not preclude a linear effect for the whole birth weight SDS distribution. Our findings suggest that low birth weight is unlikely to be the main cause for the association between intrauterine nicotine exposure and higher BMI in later life. Alternative mechanisms, such as alterations in the noradrenergic system or increased food efficiency, have to be considered.

Prenatal organochlorine compound exposure, rapid weight gain, and overweight in infancy

BACKGROUND

Although it has been hypothesized that fetal exposure to endocrine-disrupting chemicals may increase obesity risk, empirical data are limited, and it is uncertain how early in life any effects may begin.

OBJECTIVES

We explored whether prenatal exposure to several organochlorine compounds (OCs) is associated with rapid growth in the first 6 months of life and body mass index (BMI) later in infancy.

METHODS

Data come from the INMA (Infancia y Medio-Ambiente) Child and Environment birth cohort in Spain, which recruited 657 women in early pregnancy. Rapid growth during the first 6 months was defined as a change in weight-for-age z-scores > 0.67, and elevated BMI at 14 months, as a z-score ≥ the 85th percentile. Generalized linear models were used to estimate the risk of rapid growth or elevated BMI associated with 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (DDE), hexachlorobenzene, β-hexachlorohexane, and polychlorinated biphenyls in first-trimester maternal serum.

RESULTS

After multivariable adjustment including other OCs, DDE exposure above the first quartile was associated with doubling of the risk of rapid growth among children of normal-weight (BMI < 25 kg/m2), but not overweight, mothers. DDE was also associated with elevated BMI at 14 months (relative risk per unit increase in log DDE = 1.50; 95% confidence interval, 1.11-2.03). Other OCs were not associated with rapid growth or elevated BMI after adjustment.

CONCLUSIONS

In this study we found prenatal DDE exposure to be associated with rapid weight gain in the first 6 months and elevated BMI later in infancy, among infants of normal-weight mothers. More research exploring the potential role of chemical exposures in early-onset obesity is needed.

Maternal smoking during pregnancy and subcutaneous fat mass in early childhood. The Generation R Study

Maternal smoking during pregnancy increases the risk of obesity in the offspring. Not much is known about the associations with other measures of body composition. We assessed the associations of maternal smoking during pregnancy with the development of subcutaneous fat mass measured as peripheral and central skinfold thickness measurements in early childhood, in a population-based prospective cohort study from early fetal life onward in the city of Rotterdam, The Netherlands. The study was performed in 907 mothers and their children at the ages of 1.5, 6 and 24 months. As compared to non-smoking mothers, mothers who continued smoking during pregnancy were more likely to have a younger age and a lower educational level. Their children had a lower birth weight, higher risk of small size for gestational age and were breastfed for a shorter duration (P-values <0.01). We did not observe differences in peripheral, central and total subcutaneous fat mass between the offspring of non-smoking mothers, mothers who smoked in first trimester only and mothers who continued smoking during pregnancy (P > 0.05). Also, the reported number of cigarettes smoked by mothers in both first and third trimester of pregnancy were not associated with peripheral, central and total subcutaneous fat mass in the offspring at the ages of 1.5, 6 and 24 months. Our findings suggest that fetal exposure to cigarette smoke during pregnancy does not influence subcutaneous fat mass in early childhood. Follow-up studies are needed in children at older ages and to identify associations of maternal smoking during pregnancy with other measures of body composition.

Potential latent effects of prenatal cocaine exposure on growth and the risk of cardiovascular and metabolic disease in childhood

The literature strongly suggests that prenatal exposure to certain medications and substances does not cause major malformations in early childhood. However, these exposures may have far-reaching latent health effects, such as restricted growth, hypertension, and cardiovascular events in adulthood. We reviewed the literature to identify the effects of prenatal cocaine exposure on growth and the risk of cardiovascular and metabolic disease in late adolescence and early adulthood by examining studies that were published in peer-reviewed English-language journals from 1990 through 2009 and indexed in MEDLINE. We found that animal and clinical studies of the influence of prenatal cocaine exposure on child and adolescent growth and the subsequent development of myocardial and cardiometabolic disease risk factors are few and inconclusive. Studies support the hypothesis that vascular and hemodynamic functions are partially programmed in early life and thus substantially influence vascular aging and arterial stiffening in later life. Sub-optimal fetal nutrition and growth may increase blood pressure and the development of cardiovascular and metabolic disease in late life. How prenatal cocaine and other drug exposure effects this relationship is currently unknown. Despite high rates of cocaine and other drug use during pregnancy (up to 18% in some studies), little is known about the health effects of prenatal cocaine exposure in adolescence and early adulthood. The few studies of early growth deficits persisting into adolescence are inconclusive. The literature provides little information on how exposed children grow into adulthood and about their subsequent risk of cardiometabolic and vascular disease.

In utero exposure to maternal smoking and women's risk of fetal loss in the Norwegian Mother and Child Cohort (MoBa)

BACKGROUND

Whether in utero exposure to tobacco smoke increases a woman's risk of fetal loss later in life is unknown, though data on childhood exposure suggest an association may exist. This study evaluated the association between in utero exposure to tobacco smoke and fetal loss in the Norwegian Mother and Child Cohort Study (MoBa), which enrolled ∼40% of the pregnant women in Norway from 1999 to 2008.

METHODS

Information on exposure to tobacco smoke in utero, the woman's own smoking behavior during pregnancy and other factors was obtained by a questionnaire completed at ∼17 weeks of gestation. Subsequent late miscarriage (fetal death <20 weeks) and stillbirth (fetal death ≥ 20 weeks) were ascertained from the Norwegian Medical Birth Registry. This analysis included 76 357 pregnancies (MoBa data set version 4.301) delivered by the end of 2008; 59 late miscarriages and 270 stillbirths occurred. Cox proportional hazards models were fit for each outcome and for all fetal deaths combined.

RESULTS

The adjusted hazard ratio (HR) of late miscarriage was 1.23 [95% confidence interval (CI), 0.72-2.12] in women with exposure to maternal tobacco smoke in utero when compared with non-exposed women. The corresponding adjusted HR for stillbirths was 1.11 (95% CI, 0.85-1.44) and for all fetal deaths combined, it was 1.12 (95% CI, 0.89-1.43).

CONCLUSIONS

The relatively wide CI around the HR for miscarriage reflected the limited power to detect an association, due to enrollment around 17 weeks of gestation. However, for in utero exposure to tobacco smoke and risk of stillbirth later in life, where the study power was adequate, our data provided little support for an association.

Insulin resistance in children: consensus, perspective, and future directions

OBJECTIVE

Emerging data indicate that insulin resistance is common among children and adolescents and is related to cardiometabolic risk, therefore requiring consideration early in life. However, there is still confusion on how to define insulin resistance, how to measure it, what its risk factors are, and whether there are effective strategies to prevent and treat it. A consensus conference was organized in order to clarify these points.

PARTICIPANTS

The consensus was internationally supported by all the major scientific societies in pediatric endocrinology and 37 participants.

EVIDENCE

An independent and systematic search of the literature was conducted to identify key articles relating to insulin resistance in children.

CONSENSUS PROCESS

The conference was divided into five themes and working groups: background and definition; methods of measurement and screening; risk factors and consequences; prevention; and treatment. Each group selected key issues, searched the literature, and developed a draft document. During a 3-d meeting, these papers were debated and finalized by each group before presenting them to the full forum for further discussion and agreement.

CONCLUSIONS

Given the current childhood obesity epidemic, insulin resistance in children is an important issue confronting health care professionals. There are no clear criteria to define insulin resistance in children, and surrogate markers such as fasting insulin are poor measures of insulin sensitivity. Based on current screening criteria and methodology, there is no justification for screening children for insulin resistance. Lifestyle interventions including diet and exercise can improve insulin sensitivity, whereas drugs should be implemented only in selected cases.

Will our children be healthy adults? Applying science to public health policy

Cardiovascular disease is predicted to be a leading cause of death and disability worldwide for the foreseeable future. Observational studies link a variety of prevalent early life experiences (for example, smoking in pregnancy, child poverty) to increased risk of adult cardiovascular disease. Experimental animal studies suggest plausible causal relationships. However, there has been little consideration of how to use this wealth of information to benefit children's futures. Policy documents have drawn on research evidence to recognise that early experience influences life chances, the development of human capital, and long-term health. This has led to a general policy emphasis on prevention and early intervention. To date, there are few examples of the evidence base being useful in shaping specific policies, despite potential to do so, and some examples of policy misunderstanding of science. Minor changes to the perspectives of epidemiological research in this area might greatly increase the potential for evidence-based policy.

Growth in utero and body mass index at age 5 years in children of smoking and non-smoking mothers

BACKGROUND

High birth weight is associated with overweight later in life, while tobacco exposure in utero is associated with low birth weight, but with later risk of overweight.

AIMS

To examine whether body mass index (BMI) z-scores of children at age 5 are associated with measurements of mid-abdominal diameter (MAD) in utero comparing smoking and non-smoking mothers.

STUDY DESIGN

Growth in utero was recorded as MAD in mm per days of gestational age (MAD for gestational age) at 17, 25, 33 and 37 weeks of gestation in 561 infants whose mothers participated in a population-based study in Scandinavia (1986-1988).

OUTCOME MEASURES

The offspring's BMI z-score at 5 years was used as a dependent variable, and MAD for gestational age as well as birth weight divided by gestational age in days were included as explanatory variables in separate linear regression models. Maternal BMI was considered as a potential confounder.

RESULTS

At 17 and 25 weeks gestation there were no relevant differences in MAD for gestational age between smokers and non-smokers. At 33 and 37 weeks gestation, children of smoking mothers had less increase in MAD than children of non-smoking mothers. In adjusted models, MAD for gestational age in week 33 and 37 was positively associated with BMI z-score at 5 years of age among children of both smoking and non-smoking mothers.

CONCLUSIONS

In this study overweight in children exposed to tobacco smoking in utero was apparently not mediated through foetal growth retardation, followed by enhanced fat accretion after birth.

Prenatal environmental tobacco smoke exposure and early childhood body mass index

Maternal smoking during pregnancy is associated with increased risk of childhood overweight body mass index (BMI). Less is known about the association between prenatal secondhand tobacco smoke (SHS) exposure and childhood BMI. We followed 292 mother-child dyads from early pregnancy to 3 years of age. Prenatal tobacco smoke exposure during pregnancy was quantified using self-report and serum cotinine biomarkers. We used linear mixed models to estimate the association between tobacco smoke exposure and BMI at birth, 4 weeks, and 1, 2 and 3 years. During pregnancy, 15% of women reported SHS exposure and 12% reported active smoking, but 51% of women had cotinine levels consistent with SHS exposure and 10% had cotinine concentrations indicative of active smoking. After adjustment for confounders, children born to active smokers (self-report or serum cotinine) had higher BMI at 2 and 3 years of age, compared with unexposed children. Children born to women with prenatal serum cotinine concentrations indicative of SHS exposure had higher BMI at 2 (mean difference [MD] 0.3 [95% confidence interval -0.1, 0.7]) and 3 (MD 0.4 [0, 0.8]) years compared with unexposed children. Using self-reported prenatal exposure resulted in non-differential exposure misclassification of SHS exposures that attenuated the association between SHS exposure and BMI compared with serum cotinine concentrations. These findings suggest active and secondhand prenatal tobacco smoke exposure may be related to an important public health problem in childhood and later life. In addition, accurate quantification of prenatal secondhand tobacco smoke exposures is essential to obtaining valid estimates.

Early-life determinants of overweight and obesity: a review of systematic reviews

The aim of this paper was to review the evidence for early-life (from conception to 5 years of age) determinants of obesity. The design is review of published systematic reviews. Data sources included Medline, Embase, Web of Science, Cochrane Library, CINAHL, PsycINFO. Identification of 22 eligible reviews from a database of 12,021 independent publications. Quality of selected reviews assessed using the Assessment of Multiple Systematic Reviews score. Articles published after the reviews were used to confirm results. No review was classified as high quality, 11 as moderate and 11 as low. Factors associated with later overweight and obesity: maternal diabetes, maternal smoking, rapid infant growth, no or short breastfeeding, obesity in infancy, short sleep duration, <30 min of daily physical activity, consumption of sugar-sweetened beverages. Other factors were identified as potentially relevant, although the size of their effect is difficult to estimate. Maternal smoking, breastfeeding, infant size and growth, short sleep duration and television viewing are supported by better-quality reviews. It is difficult to establish a causal association between possible determinants and obesity, and the relative importance of each determinant. Future research should focus on early-life interventions to confirm the role of protective and risk factors and to tackle the high burden obesity represents for present and future generations.