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

Vaporized nicotine in utero results in reduced birthweight, increased locomotion, and decreased voluntary exercise, dependent on sex and diet in offspring

Rationale Clinical research has shown that prenatal exposure to nicotine may result in increased obesity risk later in life. Preclinical research has corroborated this finding, but few studies have investigated inhaled nicotine or the interaction with diet on obesity risk. Objective The aim of this study was to investigate the effects of prenatal nicotine exposure on both direct and indirect obesity measures, with both sex and diet as factors. Methods Pregnant rats were exposed to either vehicle or nicotine vapor (24 mg/mL or 59 mg/mL) throughout the entire gestational period. Offspring from each treatment group were given either a normal diet or a high fat diet starting at postnatal day 22. Caloric intake, body weight, spontaneous locomotion, sleep/wake activity, and voluntary exercise were measured throughout adolescence. Pregnancy weight gain and pup birthweights were collected to further measure developmental effects of prenatal nicotine exposure. Results Both maternal weight gain during pregnancy and pup weight at birth were decreased with prenatal nicotine exposure. Early adolescent males showed increased spontaneous activity in the open field following prenatal nicotine exposure compared to vehicle counterparts, particularly those given high-fat diet. Additionally, high dose nicotine prenatal treated males ran significantly less distance on the running wheel in late adolescence compared to vehicle counterparts, in the normal diet group only. Conclusion The results presented here show decreased birthweight, hyperactivity, and decreased voluntary exercise in adolescence following prenatal nicotine exposure in dose, sex, and diet dependent manners, which could lead to increased obesity risk in adulthood.

Prenatal environmental exposures associated with sex differences in childhood obesity and neurodevelopment

BACKGROUND

Obesity and neurodevelopmental delay are complex traits that often co-occur and differ between boys and girls. Prenatal exposures are believed to influence children's obesity, but it is unknown whether exposures of pregnant mothers can confer a different risk of obesity between sexes, and whether they can affect neurodevelopment.

METHODS

We analyzed data from 1044 children from the HELIX project, comprising 93 exposures during pregnancy, and clinical, neuropsychological, and methylation data during childhood (5-11 years). Using exposome-wide interaction analyses, we identified prenatal exposures with the highest sexual dimorphism in obesity risk, which were used to create a multiexposure profile. We applied causal random forest to classify individuals into two environments: E1 and E0. E1 consists of a combination of exposure levels where girls have significantly less risk of obesity than boys, as compared to E0, which consists of the remaining combination of exposure levels. We investigated whether the association between sex and neurodevelopmental delay also differed between E0 and E1. We used methylation data to perform an epigenome-wide association study between the environments to see the effect of belonging to E1 or E0 at the molecular level.

RESULTS

We observed that E1 was defined by the combination of low dairy consumption, non-smokers' cotinine levels in blood, low facility richness, and the presence of green spaces during pregnancy (OR_interaction = 0.070, P = 2.59 × 10^-5). E1 was also associated with a lower risk of neurodevelopmental delay in girls, based on neuropsychological tests of non-verbal intelligence (OR_interaction = 0.42, P = 0.047) and working memory (OR_interaction = 0.31, P = 0.02). In line with this, several neurodevelopmental functions were enriched in significant differentially methylated probes between E1 and E0.

CONCLUSIONS

The risk of obesity can be different for boys and girls in certain prenatal environments. We identified an environment combining four exposure levels that protect girls from obesity and neurodevelopment delay. The combination of single exposures into multiexposure profiles using causal inference can help determine populations at risk.

Early childhood exposure to maternal smoking and obesity: A nationwide longitudinal survey in Japan

Involuntary exposure to tobacco smoke is suspected to be one of the risks factors that are associated with obesity in children. The purpose of this study was to examine the relationship between early childhood exposure to tobacco smoke and the risk of obesity and overweight in Japan. This study utilized a nationwide, population-based longitudinal survey. The participants were restricted to 32 081 children who had available information on maternal smoking history as well as childhood height and weight. We conducted a binomial log-linear regression analysis with children of non-smoking mothers as the reference group. The children with mothers who were smokers had a higher risk of developing obesity or being overweight compared to the children with mothers who were nonsmokers. The risk ratios were 1.20 (95% confidence interval [CI]: 1.09-1.32) for overweight and 1.17 (95% CI: 0.95-1.44) for obesity. Early exposure to maternal smoking increases the risk of being overweight and having obesity during childhood. The increased risk is more pronounced among children with mothers, smoked heavily, or parents, who were smokers.

Early-life exposure to tobacco and childhood adiposity: Identifying windows of susceptibility

BACKGROUND

Early-life exposure to tobacco is associated with obesity, but the most susceptible developmental periods are unknown.

OBJECTIVE

To explore windows of susceptibility in a cohort of 568 mother-child pairs.

METHODS

We measured seven measures of tobacco exposure (five self-reported and two biomarkers) spanning from pre-conception to age 5 years. Mothers self-reported active smoking (pre-conception, 17 weeks, and delivery) and household smokers (5 and 18 months postnatally). Cotinine was measured in maternal urine (27 weeks) and child urine (5 years). Adiposity (fat mass percentage) was measured at birth and 5 years via air displacement plethysmography. Using a multiple informant approach, we tested whether adiposity (5 years) and changes in adiposity (from birth to 5 years) differed by the seven measures of tobacco exposure.

RESULTS

The associations may depend on timing. For example, only pre-conception (β = 3.1%; 95% CI: 1.0-5.1) and late gestation (β = 4.0%; 95% CI: 0.4-7.6) exposures influenced adiposity accretion from birth to 5 years (p for interaction = 0.01). Early infancy exposure was also associated with 1.7% higher adiposity at 5 years (95% CI: 0.1-3.2). Mid-pregnancy and early childhood exposures did not influence adiposity.

CONCLUSIONS

Pre-conception, late gestation, and early infancy exposures to tobacco may have the greatest impact on childhood adiposity.

Prenatal Effects of Nicotine on Obesity Risks: A Narrative Review

Nicotine usage by mothers throughout pregnancy has been observed to relate to numerous deleterious effects in children, especially relating to obesity. Children who have prenatally been exposed to nicotine tend to have lower birth weights, with an elevated risk of becoming overweight throughout development and into their adolescent and adult life. There are numerous theories as to how this occurs: catch-up growth theory, thrifty phenotype theory, neurotransmitter or endocrine imbalances theory, and a more recent examination on the genetic factors relating to obesity risk. In addition to the negative effect on bodyweight and BMI, individuals with obesity may also suffer from numerous comorbidities involving metabolic disease. These may include type 1 and 2 diabetes, high cholesterol levels, and liver disease. Predisposition for obesity with nicotine usage may also be associated with genetic risk alleles for obesity, such as the DRD2 A1 variant. This is important for prenatally nicotine-exposed individuals as an opportunity to provide early prevention and intervention of obesity-related risks.

Epidemiology of Obesity

Obesity is in theory defined on the basis of the excess health risk caused by adiposity exceeding the size normally found in the population, but for practical reasons, the World Health Organization (WHO) has defined obesity as a body mass index (weight (kg)/height (m)²) of 30 or above for adults. WHO considers the steep increases in prevalence of obesity in all age groups, especially since the 1970s as a global obesity epidemic. Today, approximately 650 million adult people and approximately 340 million children and adolescence (5-19 years) suffer from obesity. It is generally more prevalent among women and older age groups than among men and younger age groups. Beyond the necessity of availability of food, evidence about causes of obesity is still very limited. However, studies have shown that obesity 'runs in families', where both genetics and environmental, and especially social, factors play important roles. Obesity is associated with an increased risk of many adverse medical, mental and social consequences, including a strong relation to type 2 diabetes. Type 2 diabetes and related metabolic syndrome and diseases are major contributors to the excess morbidity and mortality associated with obesity.

Impact of Prenatal Exposure to Smoking on Child Health

Prenatal exposure to tobacco smoke remains common, through active smoking and/or passive environmental exposure, and is linked to adverse childhood outcomes. Not only have high-quality studies and meta-analyses demonstrated increased risks of prenatal as well as postnatal complications, but adverse child outcomes are well described. In utero exposure to tobacco smoke has been associated with congenital anomalies, infant and teenager overweight and obesity, and neuropsychiatric sequelae. In addition, certain childhood malignancies have been linked to paternal smoking during pregnancy. In this chapter, adverse childhood outcomes related to intrauterine exposure to electronic cigarettes and marijuana are described.

Endocrine Disruptors and Obesity: an Overview

Obesity is a growing pandemic. Endocrine-disrupting chemicals are widespread in the environment. In this perspective, the authors examine the issue related to the exposure to several chemicals with endocrine-disrupting properties as promoting factors to obesity. Data show that Phthalates, Bisphenol compounds, Persistent Organic Pollutants (POPs), solvents, and personal care products can modify metabolic properties in a dose-response and sex-specific manner. Phthalates and bisphenol compounds increase body mass index, waist circumference, waist to height ratio, and the sum of skinfold thicknesses in women and not in men. Low-dose exposure to Persistent Organic Pollutants is strongly associated with increased body mass index in men and decreased this parameter in women. The mechanism through which these compounds act on anthropometric parameters is not entirely understood. Several studies suggest a possible interference in gonadotropin secretion and the thyroid axis. These inspire a decrease of both total and free testosterone levels in men and FT3 and FT4 levels in women, particularly after a pregnancy. The impact of endocrine disruptor chemicals on adipose tissue inflammation and future cardio-metabolic disorders remains to be elucidated. Therefore, studies involving both healthy and obese individuals are needed to unambiguously confirm results from in vitro and animal models.

Maternal smoking status during pregnancy and low birth weight in offspring: systematic review and meta-analysis of 55 cohort studies published from 1986 to 2020

BACKGROUND

Maternal smoking during pregnancy may be associated with low birth weight (LBW) in offspring and global risk estimates have not been summarized previously. We aimed to systematically explore evidence regarding maternal smoking and the LBW risk in offspring globally and examine possible causes of heterogeneity across relevant studies.

METHODS

Comprehensive search of PubMed, Ovid Embase, Ovid Medline (R), and Web of science from inception until October 2021 was carried out. A random-effects meta-analysis was used to estimate the pooled odds ratio (OR) and corresponding 95% confidence interval (CI). Restricted cubic spline analysis with three knots was used to further examine the dose-response relationship.

RESULTS

Literature searches yielded 4940 articles, of which 53 met inclusion criteria (comprising 55 independent studies). Maternal smoking during pregnancy was significantly associated with the risk of LBW in offspring (OR = 1.89, 95% CI = 1.80-1.98). Furthermore, an obvious dose-response relationship between the amount of cigarettes daily smoked in pregnancy and the risk of LBW in offspring was observed. The results of subgroup analyses indicated that the risk of maternal smoking on LBW was larger in more recently conducted studies (P = 0.020) and longer period of active smoking during pregnancy (P = 0.002). No evidence of publication bias was found.

CONCLUSIONS

In summary, maternal smoking in pregnancy was significantly associated with a higher risk of LBW in offspring on a global scale. The risk of maternal smoking on infant LBW seems to be increasing over time, and was higher with longer smoking duration throughout pregnancy and more cigarettes smoked daily.

Effect of Exposure to Paternal Smoking on Overweight and Obesity in Children: Findings from the Children Lifeway Cohort in Shenzhen, Southern China

INTRODUCTION

Paternal smoking associated with childhood overweight and obesity has been a concern, but studies have not investigated smoking exposure and smoking details. We investigated the association of exposures from paternal smoking as well as smoking details on offspring overweight/obesity.

METHODS

A total of 4,513 children (aged 7-8 years) in Shenzhen were enrolled. Four different exposures from paternal smoking as well as smoking quantity, duration of smoking, and age of starting smoking details were the exposure variables and demographic characteristics, and circumstances of birth, dietary intake, lifestyle, and nonpaternal-smoking exposure were covariates in the logistic regression analysis to determine the effect of paternal smoking on childhood overweight/obesity, estimating odds ratios (ORs), and 95% confidence intervals (CIs).

RESULTS

Paternal smoking was positively associated with childhood overweight/obesity (p < 0.05). Moreover, only preconception exposure, and both pre- and postconception exposure were significantly associated with childhood overweight/obesity (OR 1.54 [95% CI: 1.14-2.08] and OR 1.73 [95% CI: 1.14-2.61], respectively), restricted to boys but not girls. Furthermore, for children with only preconception paternal-smoking exposure, the dose-response relation was positive between smoking quantity, duration of smoking, age at starting, and overweight/obesity for boy offspring (p trend <0.001). We did not find any significant association between only postnatal exposure to paternal smoking and childhood overweight/obesity (p > 0.05).

CONCLUSIONS

Our findings suggest that paternal smoking is associated with boys' overweight/obesity, and this association may be due to the paternal-smoking exposure before conception rather than the postnatal exposure to paternal smoking. Reducing paternal-smoking exposure before conception might help reduce overweight/obesity in boys.

Childhood exposure to parental smoking and life-course overweight and central obesity

OBJECTIVE

To evaluate the association between childhood parental smoking exposure and the risk of overweight/obesity from childhood to adulthood.

METHODS

This study leverages the data from two longitudinal population based cohort studies, the Cardiovascular Risk in Young Finns Study between years 1980-2011/2012 (YFS; N = 2,303; baseline age 3-18 years) and the Special Turku Coronary Risk Factor Intervention Project between years 1989-2009/2010 (STRIP; N = 632; baseline age 7 months). Weight, height and waist circumference were measured from childhood to adulthood. Overweight/obesity was defined as body mass index ≥25 kg/m2 in adults and using the Cole criteria in children. Central obesity was defined as waist circumference > 100/90 cm in men/women and as a waist-to-height ratio > 0.50 in children. Statistical analyses were adjusted for age, sex, socioeconomic status, smoking, birth weight, parental ages, diet and physical activity.

RESULTS

Childhood parental smoking exposure was associated with increased risk for life-course overweight/obesity (YFS: RR1.13, 95%CI 1.02-1.24; STRIP: RR1.57, 95%CI 1.10-2.26) and central obesity (YFS: RR1.18, 95%CI 1.01-1.38; STRIP: RR1.45, 95%CI 0.98-2.15).

CONCLUSIONS

Childhood exposure to parental smoking is associated with increased risk of overweight/obesity over the life-course. KEY MESSAGES Exposure to parental smoking in childhood was associated with increased risk of overweight/obesity, central obesity and adiposity measured by skinfold thickness from childhood to adulthood.

Phenome-wide investigation of the causal associations between childhood BMI and adult trait outcomes: a two-sample Mendelian randomization study

Background

Childhood obesity is reported to be associated with the risk of many diseases in adulthood. However, observational studies cannot fully account for confounding factors. We aimed to systematically assess the causal associations between childhood body mass index (BMI) and various adult traits/diseases using two-sample Mendelian randomization (MR).

Methods

After data filtering, 263 adult traits genetically correlated with childhood BMI (P < 0.05) were subjected to MR analyses. Inverse-variance weighted, MR-Egger, weighted median, and weighted mode methods were used to estimate the causal effects. Multivariable MR analysis was performed to test whether the effects of childhood BMI on adult traits are independent from adult BMI.

Results

We identified potential causal effects of childhood obesity on 60 adult traits (27 disease-related traits, 27 lifestyle factors, and 6 other traits). Higher childhood BMI was associated with a reduced overall health rating (β = − 0.10, 95% CI − 0.13 to − 0.07, P = 6.26 × 10⁻¹¹). Specifically, higher childhood BMI was associated with increased odds of coronary artery disease (OR = 1.09, 95% CI 1.06 to 1.11, P = 4.28 × 10⁻¹¹), essential hypertension (OR = 1.12, 95% CI 1.08 to 1.16, P = 1.27 × 10⁻¹¹), type 2 diabetes (OR = 1.36, 95% CI 1.30 to 1.43, P = 1.57 × 10⁻³⁴), and arthrosis (OR = 1.09, 95% CI 1.06 to 1.12, P = 8.80 × 10⁻⁹). However, after accounting for adult BMI, the detrimental effects of childhood BMI on disease-related traits were no longer present (P > 0.05). For dietary habits, different from conventional understanding, we found that higher childhood BMI was associated with low calorie density food intake. However, this association might be specific to the UK Biobank population.

Conclusions

In summary, we provided a phenome-wide view of the effects of childhood BMI on adult traits. Multivariable MR analysis suggested that the associations between childhood BMI and increased risks of diseases in adulthood are likely attributed to individuals remaining obese in later life. Therefore, ensuring that childhood obesity does not persist into later life might be useful for reducing the detrimental effects of childhood obesity on adult diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-021-00865-3.

Changes in parental smoking during pregnancy and risks of adverse birth outcomes and childhood overweight in Europe and North America: An individual participant data meta-analysis of 229,000 singleton births

BACKGROUND

Fetal smoke exposure is a common and key avoidable risk factor for birth complications and seems to influence later risk of overweight. It is unclear whether this increased risk is also present if mothers smoke during the first trimester only or reduce the number of cigarettes during pregnancy, or when only fathers smoke. We aimed to assess the associations of parental smoking during pregnancy, specifically of quitting or reducing smoking and maternal and paternal smoking combined, with preterm birth, small size for gestational age, and childhood overweight.

METHODS AND FINDINGS

We performed an individual participant data meta-analysis among 229,158 families from 28 pregnancy/birth cohorts from Europe and North America. All 28 cohorts had information on maternal smoking, and 16 also had information on paternal smoking. In total, 22 cohorts were population-based, with birth years ranging from 1991 to 2015. The mothers' median age was 30.0 years, and most mothers were medium or highly educated. We used multilevel binary logistic regression models adjusted for maternal and paternal sociodemographic and lifestyle-related characteristics. Compared with nonsmoking mothers, maternal first trimester smoking only was not associated with adverse birth outcomes but was associated with a higher risk of childhood overweight (odds ratio [OR] 1.17 [95% CI 1.02-1.35], P value = 0.030). Children from mothers who continued smoking during pregnancy had higher risks of preterm birth (OR 1.08 [95% CI 1.02-1.15], P value = 0.012), small size for gestational age (OR 2.15 [95% CI 2.07-2.23], P value < 0.001), and childhood overweight (OR 1.42 [95% CI 1.35-1.48], P value < 0.001). Mothers who reduced the number of cigarettes between the first and third trimester, without quitting, still had a higher risk of small size for gestational age. However, the corresponding risk estimates were smaller than for women who continued the same amount of cigarettes throughout pregnancy (OR 1.89 [95% CI 1.52-2.34] instead of OR 2.20 [95% CI 2.02-2.42] when reducing from 5-9 to ≤4 cigarettes/day; OR 2.79 [95% CI 2.39-3.25] and OR 1.93 [95% CI 1.46-2.57] instead of OR 2.95 [95% CI 2.75-3.15] when reducing from ≥10 to 5-9 and ≤4 cigarettes/day, respectively [P values < 0.001]). Reducing the number of cigarettes during pregnancy did not affect the risks of preterm birth and childhood overweight. Among nonsmoking mothers, paternal smoking was associated with childhood overweight (OR 1.21 [95% CI 1.16-1.27], P value < 0.001) but not with adverse birth outcomes. Limitations of this study include the self-report of parental smoking information and the possibility of residual confounding. As this study only included participants from Europe and North America, results need to be carefully interpreted regarding other populations.

CONCLUSIONS

We observed that as compared to nonsmoking during pregnancy, quitting smoking in the first trimester is associated with the same risk of preterm birth and small size for gestational age, but with a higher risk of childhood overweight. Reducing the number of cigarettes, without quitting, has limited beneficial effects. Paternal smoking seems to be associated, independently of maternal smoking, with the risk of childhood overweight. Population strategies should focus on parental smoking prevention before or at the start, rather than during, pregnancy.

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.

The effects of amniotic fluid and foetal cord blood cotinine concentrations on pregnancy complications and the anthropometric measurements of newborns

Our objective was determining the effects of amniotic fluid (AF) and fetal cord blood (FCB) cotinine concentrations on pregnancy complications and the anthropometric measurements in the newborns whose mothers underwent amniocentesis. This study was conducted as a case-control study, in Turkey. A total of 250 pregnant women with amniocentesis indication were recruited into the study and the cotinine levels in the AF and FCB were determined. A smoking habit did not statistically affect the incidence of pregnancy complications (p>.05). The birth weights of the newborns were negatively correlated with the AF cotinine levels. The incidences of low birth weight, low Apgar scores and RDS were positively correlated with higher levels of cotinine in AF and FCB. It is important for healthcare staff to provide training and consultancy services for the health improvement of pregnant women and the prevention of smoking during pregnancy. Impact statement What is already known on this subject? The pre-pregnancy smoking habit usually continues during the pregnancy. A significant negative correlation was present between the foetal cord blood cotinine levels and the birth weight. What do the results of this study add? The anthropometric measurements of the newborns born from mothers with high AF cotinine levels were lower than newborns born from mothers with low amniotic fluid cotinine levels. Respiratory Distress syndrome is more often determined in newborns born from mothers with high AF cotinine levels. What are the implications of these findings for clinical practice and/or further research? Future studies should be performed to investigate the effects of cigarette smoking on the health problems, the growth characteristics and the neurological development of newborns and infants within the first year of life.

The association between antibiotics in the first year of life and child growth trajectory

BACKGROUND

Antibiotics are frequently prescribed to children, and may be an environmental influence that contributes to the increasing prevalence of childhood obesity. The aim of this study was to examine the effect of antibiotic use in the first year of life on child growth trajectories from birth to age 6 years including significant covariates.

METHODS

Data from 586 children in the Infant Feeding Practices II (IFPS II) and 6 year follow-up study (6YFU) were included. Antibiotic exposures, weight and height measurements were collected from birth through the first 12 months, and then again at 6 years. Linear mixed effects growth modeling, controlling for exclusive breastfeeding, socio-demographic factors, smoking during pregnancy, gestational diabetes, and maternal pre-pregnancy weight status, was used to examine the association between antibiotic exposure and child growth trajectories through age 6 years.

RESULTS

The majority of infants (60.58%) did not receive any antibiotics; 33.79% received 1-2 courses and 5.63% received 3 or more antibiotic courses during the first year. In the unadjusted model, children with 1-2 antibiotic exposures had a 0.17 (SE 0.08) higher rate of change in BMI z-score (BMIz) than children without any antibiotics, and children with ≥3 exposures had a 0.42 (SE 0.16) higher rate of change in BMIz (p = 0.009). Growth trajectory over time for those who had ≥3 antibiotics was greater than those without any antibiotics (p = 0.002).

CONCLUSIONS

Efforts to guide the judicious use of antibiotics should continue, particularly in the first year of life.

Multiple imputation methods for handling missing values in a longitudinal categorical variable with restrictions on transitions over time: a simulation study

Background

Longitudinal categorical variables are sometimes restricted in terms of how individuals transition between categories over time. For example, with a time-dependent measure of smoking categorised as never-smoker, ex-smoker, and current-smoker, current-smokers or ex-smokers cannot transition to a never-smoker at a subsequent wave. These longitudinal variables often contain missing values, however, there is little guidance on whether these restrictions need to be accommodated when using multiple imputation methods. Multiply imputing such missing values, ignoring the restrictions, could lead to implausible transitions.

Methods

We designed a simulation study based on the Longitudinal Study of Australian Children, where the target analysis was the association between (incomplete) maternal smoking and childhood obesity. We set varying proportions of data on maternal smoking to missing completely at random or missing at random. We compared the performance of fully conditional specification with multinomial and ordinal logistic imputation, and predictive mean matching, two-fold fully conditional specification, indicator based imputation under multivariate normal imputation with projected distance-based rounding, and continuous imputation under multivariate normal imputation with calibration, where each of these multiple imputation methods were applied, accounting for the restrictions using a semi-deterministic imputation procedure.

Results

Overall, we observed reduced bias when applying multiple imputation methods with restrictions, and fully conditional specification with predictive mean matching performed the best. Applying fully conditional specification and two-fold fully conditional specification for imputing nominal variables based on multinomial logistic regression had severe convergence issues. Both imputation methods under multivariate normal imputation produced biased estimates when restrictions were not accommodated, however, we observed substantial reductions in bias when restrictions were applied with continuous imputation under multivariate normal imputation with calibration.

Conclusion

In a similar longitudinal setting we recommend the use of fully conditional specification with predictive mean matching, with restrictions applied during the imputation stage.

Electronic supplementary material

The online version of this article (10.1186/s12874-018-0653-0) contains supplementary material, which is available to authorized users.

Maternal Smoking During Pregnancy and Timing of Puberty in Sons and Daughters: A Population-Based Cohort Study

Because early puberty has been linked to diseases later in life, identification of modifiable causes of early puberty is of interest. We explored the possible associations between maternal smoking during pregnancy and pubertal development in sons and daughters. Between 2012 and 2017, 15,819 children from the Danish National Birth Cohort, born during 2000-2003, provided half-yearly information on puberty from the age of 11 years. We estimated adjusted age differences (in months) at attaining various pubertal milestones, including Tanner stages, per 10 daily cigarettes smoked in the first trimester of gestation. In sons, exposure to smoking in utero was associated with earlier genital development (Tanner 2, -1.3 months, 95% confidence interval (CI): -2.5, 0.0; Tanner 5, -3.7 months, 95% CI: -5.3, -2.0), pubic hair development (Tanner 2, -1.8 months, 95% CI: -2.9, -0.6; Tanner 5, -2.9 months, 95% CI: -4.2, -1.7), and voice break (-2.4 months, 95% CI: -3.6, -1.3). In daughters, maternal smoking was associated with earlier breast development (Tanner 2, -3.4 months, 95% CI: -5.3, -1.5; Tanner 5, -4.7 months, 95% CI: -6.5, -2.9), pubic hair development stages 3-5 (Tanner 5, -2.5 months, 95% CI: -4.1, -1.0), and menarche (-3.1 months, 95% CI: -4.0, -2.3). Fetal exposure to tobacco smoke might advance timing of puberty in boys and girls.

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 Prenatal Exposure to Cadmium With Child Growth, Obesity, and Cardiometabolic Traits

Prenatal cadmium exposure has been associated with impaired fetal growth; much less is known about the impact during later childhood on growth and cardiometabolic traits. To elucidate the associations of prenatal cadmium exposure with child growth, adiposity, and cardiometabolic traits in 515 mother-child pairs in the Rhea Mother-Child Study cohort (Heraklion, Greece, 2007-2012), we measured urinary cadmium concentrations during early pregnancy and assessed their associations with repeated weight and height measurements (taken from birth through childhood), waist circumference, skinfold thickness, blood pressure, and serum lipid, leptin, and C-reactive protein levels at age 4 years. Adjusted linear, Poisson, and mixed-effects regression models were used, with interaction terms for child sex and maternal smoking added. Elevated prenatal cadmium levels (third tertile of urinary cadmium concentration (0.571-2.658 μg/L) vs. first (0.058-0.314 μg/L) and second (0.315-0.570 μg/L) tertiles combined) were significantly associated with a slower weight trajectory (per standard deviation score) in all children (β = -0.17, 95% confidence interval (CI): -0.32, -0.02) and a slower height trajectory in girls (β = -0.30, 95% CI: -0.52,-0.09; P for interaction = 0.025) and in children born to mothers who smoked during pregnancy (β = -0.48, 95% CI: -0.83, -1.13; P for interaction = 0.027). We concluded that prenatal cadmium exposure was associated with delayed growth in early childhood. Further research is needed to understand cadmium-related sex differences and the role of coexposure to maternal smoking during early pregnancy.

A Bayesian approach to the g-formula

Epidemiologists often wish to estimate quantities that are easy to communicate and correspond to the results of realistic public health interventions. Methods from causal inference can answer these questions. We adopt the language of potential outcomes under Rubin's original Bayesian framework and show that the parametric g-formula is easily amenable to a Bayesian approach. We show that the frequentist properties of the Bayesian g-formula suggest it improves the accuracy of estimates of causal effects in small samples or when data are sparse. We demonstrate an approach to estimate the effect of environmental tobacco smoke on body mass index among children aged 4-9 years who were enrolled in a longitudinal birth cohort in New York, USA. We provide an algorithm and supply SAS and Stan code that can be adopted to implement this computational approach more generally.

Differences in maternal smoking across successive pregnancies - dose-dependent relation to BMI z-score in the offspring: an individual patient data (IPD) meta-analysis

INTRODUCTION

Uncontrolled family factors may bias the estimation of the association between maternal smoking during pregnancy and offspring body mass index (BMI). The objective was to assess if there is an association between maternal smoking during pregnancy and offspring BMI z-score independent of factors in the siblings' shared environment and if such association is linear.

METHODS

We performed an individual patient data meta-analysis using five studies providing sibling data (45,299 children from 14,231 families). In a multi-level model, separating within-family and between-family effects and with random intercept for families, we analysed the dose-response association between maternal number of cigarettes per day during pregnancy and offspring's BMI z-score using B-splines to allow for non-linear associations.

RESULTS

A linear within-family effect for number of cigarettes smoked in the range from 1 to 30 cigarettes per day on the offspring's BMI z-score was observed. Each additional cigarette per day between sibling pregnancies resulted in an increase in BMI z-score of 0.007 (95% CI [0.006, 0.009]). A between family-effect emerged only with doses ≥25 cigarettes per day.

CONCLUSIONS

The number of cigarettes mothers smoke per day during pregnancy is positively associated with offspring BMI z-score even among siblings, suggesting that the association is not entirely explained by confounding by family factors.

Population DNA methylation studies in the Developmental Origins of Health and Disease (DOHaD) framework

Epigenetic changes represent a potential mechanism underlying associations of early-life exposures and later life health outcomes. Population-based cohort studies starting in early life are an attractive framework to study the role of such changes. DNA methylation is the most studied epigenetic mechanism in population research. We discuss the application of DNA methylation in early-life population studies, some recent findings, key challenges and recommendations for future research. Studies into DNA methylation within the Developmental Origins of Health and Disease framework generally either explore associations between prenatal exposures and offspring DNA methylation or associations between offspring DNA methylation in early life and later health outcomes. Only a few studies to date have integrated prospective exposure, epigenetic and phenotypic data in order to explicitly test the role of DNA methylation as a potential biological mediator of environmental effects on health outcomes. Population epigenetics is an emerging field which has challenges in terms of methodology and interpretation of the data. Key challenges include tissue specificity, cell type adjustment, issues of power and comparability of findings, genetic influences, and exploring causality and functional consequences. Ongoing studies are working on addressing these issues. Large collaborative efforts of prospective cohorts are emerging, with clear benefits in terms of optimizing power and use of resources, and in advancing methodology. In the future, multidisciplinary approaches, within and beyond longitudinal birth and preconception cohorts will advance this complex, but highly promising, the field of research.

Diagnosis, treatment and prevention of pediatric obesity: consensus position statement of the Italian Society for Pediatric Endocrinology and Diabetology and the Italian Society of Pediatrics

The Italian Consensus Position Statement on Diagnosis, Treatment and Prevention of Obesity in Children and Adolescents integrates and updates the previous guidelines to deliver an evidence based approach to the disease. The following areas were reviewed: (1) obesity definition and causes of secondary obesity; (2) physical and psychosocial comorbidities; (3) treatment and care settings; (4) prevention.The main novelties deriving from the Italian experience lie in the definition, screening of the cardiometabolic and hepatic risk factors and the endorsement of a staged approach to treatment. The evidence based efficacy of behavioral intervention versus pharmacological or surgical treatments is reported. Lastly, the prevention by promoting healthful diet, physical activity, sleep pattern, and environment is strongly recommended since the intrauterine phase.

Childcare before age 6 and body mass index at age 7 years in a cohort of Danish children

BACKGROUND

Previous studies show inconsistent associations between childcare and obesity.

AIMS

Our prior work demonstrated that childcare in infancy was associated with higher weight in a cohort of Danish children. Here, we extend this work and examine childcare through 6 years and body mass index (BMI) at age 7 years.

MATERIALS AND METHODS

We examined 24 714 children in the Danish National Birth Cohort who were also in the Childcare Database. We conducted multivariable linear regressions examining children prior to age 6, overall and by type (daycare, crèche, age-integrated and kindergarten), and BMI z-score at 7 years, stratifying on maternal socio-occupational status.

RESULTS

A total of 19 760 (80.0%) children attended childcare before age 6. Childcare prior to age 6 was associated with BMI z-score at 7 years (0.004 units per each additional 6 months of care; 95% CI: 0.001, 0.008; p = 0.01). Childcare in a kindergarten was the only type of care associated with BMI (0.009 units; 95% CI: 0.003, 0.02; p = 0.01). For children of higher socio-occupational status mothers, childcare was associated with a 0.008 unit increase in BMI (95% CI: 0.004, 0.01; p > 0.001).

CONCLUSIONS

Childcare was weakly associated with later BMI. This relationship was more pronounced in children from higher socio-occupational status mothers and children in kindergarten care.

Smoking habit from the paternal line and grand-child's overweight or obesity status in early childhood: prospective findings from the lifeways cross-generation cohort study

BACKGROUND/OBJECTIVES

The role of smoking from the paternal line during the pre-conception period on grand-child's overweight/obesity and associated underlying pathways are uncertain. We examined whether the smoking status from the paternal line was associated with the grand-child's higher weight at birth, and overweight or obesity at 5 and 9 years of age. The grandparental smoking effect from the maternal line was also explored.

SUBJECTS/METHODS

Participants were fathers and grandparents and grand-children from the Lifeways Cross Generational Cohort (N = 1021 for the analysis at birth; N = 562 and N = 284 for the analysis at 5 and 9 years, respectively). Paternal and grandparental smoking was defined as smoking versus non-smoking. Children's weight categories compared were high versus normal weight at birth, and overweight/obesity versus normal weight (based on BMI and waist circumference) at age of five and nine years. Logistic regression models were used to estimate the crude and adjusted associations.

RESULTS

After adjustment for several child and parental factors, at age five there was an association between paternal smoking and offspring's overweight/obesity based on BMI (Adjusted Odds Ratio (AOR), and 95%CI: 1.76, 1.14-2.71, p-value: 0.010), most marked for boys (AOR: 2.05, 1.06-3.96, p-value: 0.032). These associations remained when confined to the children sample with biological fathers only (overall sample, AOR: 1.92, 1.22-3.02, p-value: 0.005; son, AOR: 2.09, 1.06-4.11, p-value: 0.033). At age 9, the paternal grandmothers' smoking was positively associated with their grandchild's overweight/obesity status based on waist circumference (AOR: 3.29, 1.29-8.37), and especially with that of her granddaughter (AOR: 3.44, 1.11-10.69). These associations remained when analysing only the children sample with biological fathers (overall sample, AOR: 3.22,1.25-8.29, p-value: 0.016; granddaughter, AOR: 3.55, 1.13-11.15, p-value: 0.030).

CONCLUSION

The smoking habit from the paternal line is associated with grand-children's adiposity measures during their early childhood, which might be epigenetically transmitted through male-germline cells.

Maternal smoking during pregnancy and offspring overweight: is there a dose-response relationship? An individual patient data meta-analysis

BACKGROUND/OBJECTIVES

A number of meta-analyses suggest an association between any maternal smoking in pregnancy and offspring overweight obesity. Whether there is a dose-response relationship across number of cigarettes and whether this differs by sex remains unclear.

SUBJECT/METHODS

Studies reporting number of cigarettes smoked during pregnancy and offspring BMI published up to May 2015 were searched. An individual patient data meta-analysis of association between the number of cigarettes smoked during pregnancy and offspring overweight (defined according to the International Obesity Task Force reference) was computed using a generalized additive mixed model with non-linear effects and adjustment for confounders (maternal weight status, breastfeeding, and maternal education) and stratification for sex.

RESULTS

Of 26 identified studies, 16 authors provided data on a total of 238,340 mother-child-pairs. A linear positive association was observed between the number of cigarettes smoked and offspring overweight for up to 15 cigarettes per day with an OR increase per cigarette of 1.03, 95% CI = [1.02-1.03]. The OR flattened with higher cigarette use. Associations were similar in males and females. Sensitivity analyses supported these results.

CONCLUSIONS

A linear dose-response relationship of maternal smoking was observed in the range of 1-15 cigarettes per day equally in boys and girls with no further risk increase for doses above 15 cigarettes.

Tobacco Exposure and Conditional Weight-for-Length Gain by 2 Years of Age

Objective

To prospectively examine dose-response and timing effects of prenatal (PTE) and postnatal tobacco exposure on obesity risk assessed by conditional weight-for-length gain (CWFLG), by 2 years of age. CWFLG over the first 2 years of life was examined for 117 PTE and 57 nonexposed children. Repeated assessments of PTE were conducted beginning in the first trimester of pregnancy, using multiple methods. PTE or postnatal exposure status was not predictive of CWFLG. However, there was a dose-response association and an association with fetal exposure ascertained by infant meconium positive for nicotine and metabolites. PTE is related to restricted growth at birth, yet associated with accelerated CWFLG by 2 years of age, a measure that controls for birthweight differences. Results highlight the importance of examining dose-response and timing of exposure associations, along with the importance of obesity risk-reduction interventions within the first 2 years of life among PTE children.

Low serum vitamin D-status, air pollution and obesity: A dangerous liaison

The aim of this review is to provide a general overview of the possible associations among the vitamin D status, air pollution and obesity. Sunlight exposure accounts in humans for more than 90 % of the production of vitamin D. Among emerging factors influencing sunlight-induced synthesis of vitamin D, prospective and observational studies proved that air pollution constitutes an independent risk factor in the pathogenesis of vitamin D hypovitaminosis. In addition, environmental pollutants can affect risk of obesity when inhaled, in combination with unhealthy diet and lifestyle. In turn, obesity is closely associated with a low vitamin D status and many possible mechanisms have been proposed to explain this association. The associations of air pollution with low vitamin D status on the hand and with obesity on the other hand, could provide a rationale for considering obesity as a further link between air pollution and low vitamin D status. In this respect, a vicious cycle could operate among low vitamin D status, air pollution, and obesity, with additive detrimental effects on cardio-metabolic risk in obese individuals. Besides vitamin D supplementation, nutrient combination, used to maximize the protective effects against air pollution, might also contribute to improve the vitamin D status by attenuating the "obesogen" effects of air pollution.

Prenatal Maternal Smoking and Increased Risk for Tourette Syndrome and Chronic Tic Disorders

OBJECTIVE

We assessed the role of prenatal maternal smoking in risk for Tourette syndrome and chronic tic disorder (TS/CT) and pediatric-onset obsessive-compulsive disorder (OCD).

METHOD

In an analysis of 73,073 singleton pregnancies from the Danish National Birth Cohort, we calculated incidence rates (IR) per 1,000 person-year for TS/CT and OCD. We then determined crude and adjusted hazard ratios and 95% CIs associated with prenatal maternal smoking, considering smoking as a dichotomous (yes/no) variable or a stratified variable (no smoking, light smoking, and heavy smoking [≥10 cigarettes/day]). Additional analyses examined the effect of maternal smoking on risk for TS/CT with other comorbid psychiatric conditions.

RESULTS

In final adjusted analyses, heavy smoking was associated with a 66% increased risk for TS/CT (adjusted hazard ratio = 1.66, 95% CI = 1.17-2.35). In addition, heavy smoking was associated with a 2-fold increased risk for TS/CT with comorbid attention-deficit/hyperactivity disorder (ADHD), and both light and heavy smoking were associated with a more than 2-fold increased risk for TS/CT with any non-ADHD psychiatric comorbidity. Our parallel analyses of pediatric-onset OCD were likely underpowered but showed similar relationships.

CONCLUSION

Prenatal maternal smoking was associated with increased risk for TS/CT as well as TS/CT with comorbid psychiatric conditions, even after adjustment for several important variables, including maternal psychiatric history, socioeconomic status, and partner smoking. Our findings point to a pathway linking prenatal tobacco exposure and altered brain development to TS/CT.

Thin mother, obese child? A review of early risk factors for obesity in offspring

PURPOSE OF REVIEW

The huge percentages of persons with obesity in many countries constitute a public health crisis. The severe consequences of obesity for physical health and emotional wellbeing already emerge in childhood. Therefore, the acknowledgment of early risk factors is essential to provide recommendations for prevention strategies. This review outlines the current state of research concerning early risk factors for obesity, that is, factors that even contribute to later obesity of the offspring during gestation. In this regard, this review specifically addresses the link between restricted eating behavior of the mother and obesity in her offspring. We systematically searched for articles in PsychINFO, PsychINDEX, MEDLINE, PubMed, MEDPILOT, and Web of Science, and we identified additional studies in bibliographies.

RECENT FINDINGS

Although some risk factors (e.g., short period of breastfeeding, gestational diabetes, and high maternal BMI) have a vast evidence base, others (e.g., restricted eating behavior and second-hand smoking) are insufficiently studied.

SUMMARY

Physical activity and diet programs in pregnancy can reduce not only the occurrence of gestational diabetes, but also the risk of inappropriate weight gain. As smoking during pregnancy and inappropriate eating behavior are associated with lower education, psychoeducation, for instance in sex education classes, could be easily conceivable.

Systematic review and meta-analysis of the association between maternal smoking in pregnancy and childhood overweight and obesity

BACKGROUND

By 2020, it is predicted that 60 million children worldwide will be overweight. Maternal smoking in pregnancy has been suggested as a contributing factor. Our objective was to systematically review studies on this, thereby expanding the evidence base for this association.

METHODS

Systematic review with meta-analysis, Prospero Registration number CRD42012002859. We searched PubMed, Embase, Global Health, Web of Science and the Grey literature. We included prevalence, cohort and cross-sectional studies involving full-term, singleton pregnancies. Published and unpublished studies through to 1 January 2015 in all languages, demonstrating an objective overweight outcome up until 18 years of age and data presented as an OR, were included. Quality assessment was undertaken using an adaption of the Newcastle-Ottawa scale. Statistical analysis was performed using Review Manager V.5.3.

FINDINGS

The meta-analysis included 39 studies of 236 687 children from Europe, Australia, North America and South America and Asia. Maternal smoking in pregnancy ranged from 5.5% to 38.7%, with the prevalence of overweight from 6.3% to 32.1% and obesity from 2.6% to 17%. Pooled adjusted ORs demonstrated an elevated odds of maternal smoking in pregnancy for childhood overweight (OR 1.37, 95% CI 1.28 to 1.46, I₂ 45%) and childhood obesity (OR 1.55, 95% CI 1.40 to 1.73, I₂ 24%).

INTERPRETATION

Our results demonstrate an association between maternal prenatal smoking and childhood overweight. This contributes to the growing evidence for the aetiology of childhood overweight, providing important information for policymakers and health professionals alike in planning cessation programmes or antismoking interventions for pregnant female smokers.

The association between passive and active tobacco smoke exposure and child weight status among Spanish children

OBJECTIVE

To assess the impact of passive and active tobacco smoke exposure, both pre- and postnatally, on child body mass index (BMI) and overweight.

METHODS

Pregnant women were enrolled into the Spanish INMA prospective birth cohort during 1997 to 2008. Tobacco smoke exposure was assessed by questionnaire and corroborated by pre- and postnatal cotinine measurements. Children were followed up until 4 years in newer subcohorts (N = 1866) and until 14 years in one older subcohort (N = 427). Child age- and sex-specific BMI Z-scores were calculated, and generalized estimating equations were used to model their relationship with repeated measures of tobacco smoke exposure.

RESULTS

Associations between prenatal passive exposure to tobacco smoke (adjusted β = 0.15, 95% CI: 0.05-0.25) and active maternal smoking (adjusted β = 0.20, 95% CI: 0.08-0.33) and child zBMI up to 4 years were observed. Stronger associations were observed in the older subcohort between both prenatal and child passive smoke exposure and zBMI up to 14 years.

CONCLUSIONS

Evidence for an effect of both passive and maternal active smoking on child postnatal growth has been provided. Although residual confounding cannot be completely ruled out, associations were robust to adjustment for a range of lifestyle factors.

Risk Factors for Childhood Obesity in the First 1,000 Days: A Systematic Review

CONTEXT

Mounting evidence suggests that the origins of childhood obesity and related disparities can be found as early as the "first 1,000 days"-the period from conception to age 2 years. The main goal of this study is to systematically review existing evidence for modifiable childhood obesity risk factors present from conception to age 2 years.

EVIDENCE ACQUISITION

PubMed, Embase, and Web of Science were searched for studies published between January 1, 1980, and December 12, 2014, of childhood obesity risk factors present during the first 1,000 days. Prospective, original human subject, English-language research with exposure occurrence during the first 1,000 days and with the outcome of childhood overweight or obesity (BMI ≥85th percentile for age and sex) collected between age 6 months and 18 years were analyzed between December 13, 2014, and March 15, 2015.

EVIDENCE SYNTHESIS

Of 5,952 identified citations, 282 studies met inclusion criteria. Several risk factors during the first 1,000 days were consistently associated with later childhood obesity. These included higher maternal pre-pregnancy BMI, prenatal tobacco exposure, maternal excess gestational weight gain, high infant birth weight, and accelerated infant weight gain. Fewer studies also supported gestational diabetes, child care attendance, low strength of maternal-infant relationship, low SES, curtailed infant sleep, inappropriate bottle use, introduction of solid food intake before age 4 months, and infant antibiotic exposure as risk factors for childhood obesity.

CONCLUSIONS

Modifiable risk factors in the first 1,000 days can inform future research and policy priorities and intervention efforts to prevent childhood obesity.

Short and long term health effects of parental tobacco smoking during pregnancy and lactation: a descriptive review

A great deal of attention has been focused on adverse effects of tobacco smoking on conception, pregnancy, fetal, and child health. The aim of this paper is to discuss the current evidence regarding short and long-term health effects on child health of parental smoking during pregnancy and lactation and the potential underlying mechanisms. Studies were searched on MEDLINE(®) and Cochrane database inserting, individually and using the Boolean ANDs and ORs, 'pregnancy', 'human lactation', 'fetal growth', 'metabolic outcomes', 'obesity', 'cardiovascular outcomes', 'blood pressure', 'brain development', 'respiratory outcomes', 'maternal or paternal or parental tobacco smoking', 'nicotine'. Publications coming from the reference list of studies were also considered from MEDLINE. All sources were retrieved between 2015-01-03 and 2015-31-05. There is overall consistency in literature about negative effects of fetal and postnatal exposure to parental tobacco smoking on several outcomes: preterm birth, fetal growth restriction, low birth weight, sudden infant death syndrome, neurodevelopmental and behavioral problems, obesity, hypertension, type 2 diabetes, impaired lung function, asthma and wheezing. While maternal smoking during pregnancy plays a major role on adverse postnatal outcomes, it may also cumulate negatively with smoking during lactation and with second-hand smoking exposure. Although this review was not strictly designed as a systematic review and the PRISMA Statement was not fully applied it may benefit the reader with a promptly and friendly readable update of the matter. This review strengthens the need to plan population health policies aimed to implement educational programs to hopefully minimize tobacco smoke exposure during pregnancy and lactation.

Addressing Childhood Obesity: Opportunities for Prevention

The overweight and obesity epidemic among children and adolescents in the United States continues to worsen, with notable racial, ethnic, and socioeconomic disparities. Risk factors for pediatric obesity include genetics; environmental and neighborhood factors; increased intake of sugar-sweetened beverages (SSBs), fast-food, and processed snacks; decreased physical activity; shorter sleep duration; and increased personal, prenatal, or family stress. Pediatricians can help prevent obesity by measuring body mass index at least yearly and providing age- and development-appropriate anticipatory guidance to families. Public policies and environmental interventions aim to make it easier for children to make healthy nutrition and physical activity choices. Interventions focused on family habits and parenting strategies have also been successful at preventing or treating childhood obesity.

Tooth matrix analysis for biomonitoring of organic chemical exposure: Current status, challenges, and opportunities

Epidemiological evidence supports associations between prenatal exposure to environmental organic chemicals and childhood health impairments. Unlike the common choice of biological matrices such as urine and blood that can be limited by short half-lives for some chemicals, teeth provide a stable repository for chemicals with half-life in the order of decades. Given the potential of the tooth bio-matrix to study long-term exposures to environmental organic chemicals in human biomonitoring programs, it is important to be aware of possible pitfalls and potential opportunities to improve on the current analytical method for tooth organics analysis. We critically review previous results of studies of this topic. The major drawbacks and challenges in currently practiced concepts and analytical methods in utilizing tooth bio-matrix are (i) no consideration of external (from outer surface) or internal contamination (from micro-odontoblast processes), (ii) the misleading assumption that whole ground teeth represent prenatal exposures (latest formed dentine is lipid rich and therefore would absorb and accumulate more organic chemicals), (iii) reverse causality in exposure assessment due to whole ground teeth, and (iv) teeth are a precious bio-matrix and grinding them raises ethical concerns about appropriate use of a very limited resource in exposure biology and epidemiology studies. These can be overcome by addressing the important limitations and possible improvements with the analytical approach associated at each of the following steps: (i) tooth sample preparation to retain exposure timing, (ii) organics extraction and pre-concentration to detect ultra-trace levels of analytes, (iii) chromatography separation, (iv) mass spectrometric detection to detect multi-class organics simultaneously, and (v) method validation, especially to exclude chance findings. To highlight the proposed improvements we present findings from a pilot study that utilizes tooth matrix biomarkers to obtain trimester-specific exposure information for a range of organic chemicals.

Early Life Predictors of Increased Body Mass Index among Indigenous Australian Children

Aboriginal and Torres Strait Islander Australians are more likely than non-Indigenous Australians to be obese and experience chronic disease in adulthood--conditions linked to being overweight in childhood. Birthweight and prenatal exposures are associated with increased Body Mass Index (BMI) in other populations, but the relationship is unclear for Indigenous children. The Longitudinal Study of Indigenous Children is an ongoing cohort study of up to 1,759 children across Australia. We used a multilevel model to examine the association between children's birthweight and BMI z-score in 2011, at age 3-9 years, adjusted for sociodemographic and maternal factors. Complete data were available for 682 of the 1,264 children participating in the 2011 survey; we repeated the analyses in the full sample with BMI recorded (n=1,152) after multilevel multiple imputation. One in ten children were born large for gestational age, and 17% were born small for gestational age. Increasing birthweight predicted increasing BMI; a 1-unit increase in birthweight z-score was associated with a 0.22-unit (95% CI:0.13, 0.31) increase in childhood BMI z-score. Maternal smoking during pregnancy was associated with a significant increase (0.25; 95% CI:0.05, 0.45) in BMI z-score. The multiple imputation analysis indicated that our findings were not distorted by biases in the missing data. High birthweight may be a risk indicator for overweight and obesity among Indigenous children. National targets to reduce the incidence of low birthweight which measure progress by an increase in the population's average birthweight may be ignoring a significant health risk; both ends of the spectrum must be considered. Interventions to improve maternal health during pregnancy are the first step to decreasing the prevalence of high BMI among the next generation of Indigenous children.