Prenatal environmental tobacco smoke exposure and early childhood body mass index

Investigating associations between maternal stress, smoking and adverse birth outcomes: evidence from the All Our Families cohort

BACKGROUND

Independently, active maternal and environmental tobacco smoke exposure and maternal stress have been linked to an increased risk of preterm birth and low birth weight. An understudied relationship is the potential for interactive effects between these risk factors.

METHODS

Data was obtained from the All Our Families cohort, a study of 3,388 pregnant women < 25 weeks gestation recruited from those receiving prenatal care in Calgary, Canada between May 2008 and December 2010. We investigated the joint effects of active maternal smoking, total smoke exposure (active maternal smoking plus environmental tobacco smoke) and prenatal stress (Perceived Stress Scale, Spielberger State-Trait Anxiety Inventory), measured at two time points (< 25 weeks and 34-36 weeks gestation), on preterm birth and low birth weight.

RESULTS

A marginally significant association was observed with the interaction active maternal smoking and Spielberger State-Trait Anxiety Inventory scores in relation to low birth weight, after imputation (aOR = 1.02, 95%CI: 1.00-1.03, p = 0.06). No significant joint effects of maternal stress and either active maternal smoking or total smoke exposure with preterm birth were observed. Active maternal smoking, total smoke exposure, Perceived Stress Scores, and Spielberger State-Trait Anxiety Inventory scores were independently associated with preterm birth and/or low birth weight.

CONCLUSIONS

Findings indicate the role of independent effects of smoking and stress in terms of preterm birth and low birthweight. However, the etiology of preterm birth and low birth weight is complex and multifactorial. Further investigations of potential interactive effects may be useful in helping to identify women experiencing vulnerability and inform the development of targeted interventions.

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.

Pre- and postnatal exposure to secondhand tobacco smoke and body composition at 12 years: periods of susceptibility

OBJECTIVE

The study aimed to identify periods of heightened susceptibility to the effects of pre- and postnatal secondhand tobacco smoke (SHS) exposure on body composition at age 12 years.

METHODS

The study used data from 217 children from the Health Outcomes and Measures of the Environment (HOME) Study, a prospective cohort in Cincinnati, Ohio. Using multiple informant models, the study estimated associations of maternal serum cotinine (16 and 26 weeks of pregnancy) and child serum cotinine concentrations (at age 12, 24, 36, and 48 months) with measures of body composition obtained with anthropometry and dual-energy x-ray absorptiometry at 12 years. We examined whether there were differences between these associations for pre- and postnatal exposure periods and potential effect measure modification by sex.

RESULTS

Postnatal cotinine concentrations were associated with higher weight, BMI, body fat and lean mass, waist circumference, and visceral, android, and gynoid fat. Each 10-fold increase in postnatal cotinine was associated with 76% increased risk of overweight or obesity (95% CI: 1.13-2.75). Associations between prenatal concentrations and measures of body composition at 12 years were generally null.

CONCLUSIONS

Postnatal exposure to SHS may increase adolescent adiposity and lean mass. Future studies should determine whether early-life exposures to SHS are associated with other cardiometabolic risk markers.

Maternal tobacco smoke exposure is associated with increased DNA methylation at human metastable epialleles in infant cord blood

Metastable epialleles (MEs) are genomic regions that are stochastically methylated prior to germ layer specification and exhibit high interindividual but low intra-individual variability across tissues. ME methylation is vulnerable to environmental stressors, including diet. Tobacco smoke (TS) exposure during pregnancy is associated with adverse impacts on fetal health and maternal micronutrient levels as well as altered methylation. Our objective was to determine if maternal smoke exposure impacts methylation at MEs. Consistent with prior studies, we observed reductions in one-carbon pathway micronutrients with gestational TS exposure, including maternal folate (P = 0.02) and vitamins B6 (P = 0.05) and B12 (P = 0.007). We examined putative MEs BOLA3, PAX8, and ZFYVE28 in cord blood specimens from 85 Newborn Epigenetics STudy participants. Gestational TS exposure was associated with elevated DNA methylation at PAX8 (+5.22% average methylation; 95% CI: 0.33% to 10.10%; P = 0.037). In human conceptal kidney tissues, higher PAX8 transcription was associated with lower methylation (R s = 0.55; P = 0.07), suggesting that the methylation levels established at MEs, and their environmentally induced perturbation, may have meaningful, tissue-specific functional consequences. This may be particularly important because PAX8 is implicated in several cancers, including pediatric kidney cancer. Our data are the first to indicate vulnerability of human ME methylation establishment to TS exposure, with a general trend of increasing levels of methylation at these loci. Further investigation is needed to determine how TS exposure-mediated changes in DNA methylation at MEs, and consequent expression levels, might affect smoking-related disease risk.

Exposure to polycyclic aromatic hydrocarbons during pregnancy and breast tissue composition in adolescent daughters and their mothers: a prospective cohort study

BACKGROUND

Polycyclic aromatic hydrocarbons (PAH), which are found in air pollution, have carcinogenic and endocrine disrupting properties that might increase breast cancer risk. PAH exposure might be particularly detrimental during pregnancy, as this is a time when the breast tissue of both the mother and daughter is undergoing structural and functional changes. In this study, we tested the hypothesis that ambient PAH exposure during pregnancy is associated with breast tissue composition, measured one to two decades later, in adolescent daughters and their mothers.

METHODS

We conducted a prospective analysis using data from a New York City cohort of non-Hispanic Black and Hispanic mother-daughter dyads (recruited 1998-2006). During the third trimester of pregnancy, women wore backpacks containing a continuously operating air sampling pump for two consecutive days that measured ambient exposure to eight carcinogenic higher molecular weight nonvolatile PAH compounds (Σ8 PAH) and pyrene. When daughters (n = 186) and mothers (n = 175) reached ages 11-20 and 29-55 years, respectively, optical spectroscopy (OS) was used to evaluate measures of breast tissue composition (BTC) that positively (water content, collagen content, optical index) and negatively (lipid content) correlate with mammographic breast density, a recognized risk factor for breast cancer. Multivariable linear regression was used to evaluate associations between ambient PAH exposure and BTC, overall and by exposure to household tobacco smoke during pregnancy (yes/no). Models were adjusted for race/ethnicity, age, and percent body fat at OS.

RESULTS

No overall associations were found between ambient PAH exposure (Σ8 PAH or pyrene) and BTC, but statistically significant additive interactions between Σ8 PAH and household tobacco smoke exposure were identified for water content and optical index in both daughters and mothers (interaction p values < 0.05). Σ8 PAH exposure was associated with higher water content (β_daughters = 0.42, 95% CI = 0.15-0.68; β_mothers = 0.32, 95% CI = 0.05-0.61) and higher optical index (β_daughters = 0.38, 95% CI = 0.12-0.64; β_mothers = 0.38, 95% CI = 0.12-0.65) in those exposed to household tobacco smoke during pregnancy; no associations were found in non-smoking households (interaction p values < 0.05).

CONCLUSIONS

Exposure to ambient Σ8 PAH and tobacco smoke during pregnancy might interact synergistically to impact BTC in mothers and daughters. If replicated in other cohorts, these findings might have important implications for breast cancer risk across generations.

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.

Urinary cotinine assessment of maternal smoking and environmental tobacco smoke exposure status and its associations with perinatal outcomes: a cross-sectional birth study

Tobacco consumption and environmental tobacco smoke (ETS) exposure remains an important public health concern. Pregnant women require particular attention as active and passive smoking during pregnancy are associated with multiple adverse perinatal outcomes. This study aimed to biochemically validate self-reported smoking and ETS exposure status among pregnant women, to more precisely ascertain its association with adverse perinatal outcomes. Data refers to 595 pregnant women who sought prenatal care in a public hospital in Porto, Portugal. A standard questionnaire on smoking and ETS-related variables was completed. Urinary cotinine (UC) concentrations were assessed by solid-phase competitive ELISA, in maternal urine samples collected on the day of delivery. The results showed that the optimal UC cut-off value to distinguish smokers from non-smokers and within non-smokers those who were exposed to ETS from those non-exposed in the third trimester of pregnancy was 74.1 ng/mL (sensitivity and specificity of 96.7% and 98.0%, respectively) and 1.6 ng/mL (sensitivity of 66.2% and specificity of 75.7%, respectively). The agreement between maternal self-reported and UC-based smoking status was very good (κ=0.919, p<0.001), but much lower for ETS exposure (κ=0.386, p<0.001). Maternal active smoking in the third trimester of pregnancy was associated with a significant decrease in birth weight, length and head circumference of 157.66 g (95% CI: -245.81, -69.52; p<0.001), 0.78 cm (95% CI: -1.22, -0.34; p=0.001) and 0.39 cm (95% CI: -0.70, -0.07; p=0.016), respectively. Maternal ETS exposure in the third trimester of pregnancy was associated with a non-significant increase in birth weight of 38.37 g (95% CI: -28.91, 105.64; p=0.263). Furthermore, maternal smoking cessation was associated with the increase of approximately 172 g in birth weight (95% CI: 50.00, 293.19). As such, there is an urgent need for increased public health awareness campaigns to encourage smoking cessation during pregnancy, in order to improve perinatal outcomes.

Joint effects of ambient air pollution and maternal smoking on neonatal adiposity and childhood BMI trajectories in the Healthy Start study

Coexposure to air pollution and tobacco smoke may influence early-life growth, but few studies have investigated their joint effects. We examined the interaction between fetal exposure to maternal smoking and ozone (O₃) or fine particulate matter (PM_2.5) on birth weight, neonatal adiposity, and body mass index (BMI) trajectories through age 3 years.

Methods

Participants were 526 mother-child pairs, born ≥37 weeks. Cotinine was measured at ~27 weeks gestation. Whole pregnancy and trimester-specific O₃ and PM_2.5 were estimated via. inverse-distance weighted interpolation from stationary monitors. Neonatal adiposity (fat mass percentage) was measured via. air displacement plethysmography. Child weight and length/height were abstracted from medical records. Interaction was assessed by introducing cotinine (<31.5 vs. ≥31.5 ng/mL [indicating active smoking]), O₃/PM_2.5 (low [tertiles 1-2] vs. high [tertile 3]), and their product term in linear regression models for birth weight and neonatal adiposity and mixed-effects models for BMI trajectories.

Results

The rate of BMI growth among offspring jointly exposed to maternal smoking and high PM_2.5 (between 8.1 and 12.7 μg/m³) in the third trimester was more rapid than would be expected due to the individual exposures alone (0.8 kg/m² per square root year; 95% CI = 0.1, 1.5; P for interaction = 0.03). We did not detect interactions between maternal smoking and O₃ or PM_2.5 at any other time on birth weight, neonatal adiposity, or BMI trajectories.

Conclusions

Although PM_2.5 was generally below the EPA annual air quality standards of 12.0 μg/m³, exposure during the third trimester may influence BMI trajectories when combined with maternal smoking.

Prenatal tobacco smoke exposure and neurological impairment at 10 years of age among children born extremely preterm: a prospective cohort

OBJECTIVE

To determine the association between prenatal tobacco smoke exposure and neurological impairment at 10 years of age among children born extremely preterm (<28 weeks of gestation).

DESIGN

The Extremely Low Gestational Age Newborn (ELGAN) Study, a prospective cohort.

SETTING

Ten-year follow-up of extremely preterm infants born at 14 US hospitals between 2002 and 2004.

METHODS

Prenatal tobacco smoke exposure was defined as a mother's report at enrolment of active (i.e. maternal) and passive smoking during pregnancy. Poisson regression with generalized estimating equations was used. Models adjusted for mother's age, race/ethnicity, education, insurance, pre-pregnancy body mass index, US region, multiple gestation and infant's sex; and in sensitivity analysis, gestational age at delivery and clinical subtype of preterm birth, given their classification as intermediate and non-confounding variables.

MAIN OUTCOMES

Neurological impairment at 10 years, epilepsy, cerebral palsy and cognitive impairment.

RESULTS

Of 1200 ELGAN study survivors, 856 were assessed at 10 years of age with neurological outcomes, of whom 14% (118/856) had active tobacco exposure during pregnancy and 24% (207/852) had passive tobacco exposure. Compared with children who were not exposed prenatally to tobacco, children exposed to active tobacco use during pregnancy had a higher risk of epilepsy (14% versus 5%; adjusted relative risk: 1.68, 95% CI 1.45-1.92). This risk remained after adjustment for gestational age at delivery and clinical subtype of preterm birth. Prenatal tobacco smoke exposure was not associated with other assessed neurological outcomes, including cerebral palsy and multiple measures of cognitive impairment.

CONCLUSIONS

Among children born extremely preterm, prenatal active tobacco smoke exposure was associated with an increased risk of epilepsy at 10 years of life.

TWEETABLE ABSTRACT

Among infants born before 28 weeks of gestation, prenatal active tobacco smoke exposure was associated with an increased risk of epilepsy at 10 years of life.

Cooking, smoking, and stunting: Effects of household air pollution sources on childhood growth in India

This paper investigates the effects of household air pollution (HAP) on child stunting in India using a sample of 206, 898 under-five children from the latest National Family Health Survey (2015-16). Descriptive statistics and multivariate analysis were used to understand the association of stunting by type of cooking fuel, separate kitchen, and indoor smoking in the household. Using clean cooking fuels (CCFs), having a separate kitchen, and being unexposed to smoking can reduce the prevalence of stunting by 4%, 1%, and 1%, respectively, from the current prevalence of stunting (38%). The probability of childhood stunting among children living in households using unclean cooking fuel (UCF) was significantly higher (OR-1.16; 95% CI: 1.13-1.19) than those living in households using CCF. Findings were similar results in the absence of separate kitchen (OR-1.08; 95% CI: 1.05-1.10) and exposure to environmental tobacco smoke (OR-1.06; 95% CI: 1.04-1.08). Households using UCF had a 16% higher likelihood of stunting, while there was a strong gradient of HAP with stunting after controlling socioeconomic and demographic factors. Therefore, the LPG programs, such as the Pradhan Mantri Ujjwala Yojana, may be crucial to reduce HAP and its adverse impact on stunting, and successively to achieve sustainable development goals.

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.

Design and Rationale of the Biomarker Center of the Household Air Pollution Intervention Network (HAPIN) Trial

BACKGROUND

Biomarkers of exposure, susceptibility, and effect are fundamental for understanding environmental exposures, mechanistic pathways of effect, and monitoring early adverse outcomes. To date, no study has comprehensively evaluated a large suite and variety of biomarkers in household air pollution (HAP) studies in concert with exposure and outcome data. The Household Air Pollution Intervention Network (HAPIN) trial is a liquified petroleum gas (LPG) fuel/stove randomized intervention trial enrolling 800 pregnant women in each of four countries (i.e., Peru, Guatemala, Rwanda, and India). Their offspring will be followed from birth through 12 months of age to evaluate the role of pre- and postnatal exposure to HAP from biomass burning cookstoves in the control arm and LPG stoves in the intervention arm on growth and respiratory outcomes. In addition, up to 200 older adult women per site are being recruited in the same households to evaluate indicators of cardiopulmonary, metabolic, and cancer outcomes.

OBJECTIVES

Here we describe the rationale and ultimate design of a comprehensive biomarker plan to enable us to explore more fully how exposure is related to disease outcome.

METHODS

HAPIN enrollment and data collection began in May 2018 and will continue through August 2021. As a part of data collection, dried blood spot (DBS) and urine samples are being collected three times during pregnancy in pregnant women and older adult women. DBS are collected at birth for the child. DBS and urine samples are being collected from the older adult women and children three times throughout the child's first year of life. Exposure biomarkers that will be longitudinally measured in all participants include urinary hydroxy-polycyclic aromatic hydrocarbons, volatile organic chemical metabolites, metals/metalloids, levoglucosan, and cotinine. Biomarkers of effect, including inflammation, endothelial and oxidative stress biomarkers, lung cancer markers, and other clinically relevant measures will be analyzed in urine, DBS, or blood products from the older adult women. Similarly, genomic/epigenetic markers, microbiome, and metabolomics will be measured in older adult women samples.

DISCUSSION

Our study design will yield a wealth of biomarker data to evaluate, in great detail, the link between exposures and health outcomes. In addition, our design is comprehensive and innovative by including cutting-edge measures such as metabolomics and epigenetics. https://doi.org/10.1289/EHP5751.

The association between secondhand smoke exposure and growth outcomes of children: A systematic literature review

INTRODUCTION

The strong relation between maternal smoking and maternal secondhand smoke (SHS) exposure and the growth of newborn infants has been proven. However, the effect of SHS on growth outcomes of older children is not well defined. Through a systematic literature review, we sought to determine whether a relationship exists between SHS exposure and growth outcomes of children up to 8 years of age.

METHODS

A systematic review was performed, including articles published between 2004–2019, related to SHS exposure (prenatal and postnatal) and children’s growth (weight, length/height, and head circumference). The relevant articles were identified from Science Direct, ProQuest, Sage Publication, Scopus, Wiley Online Library, CINAHL Plus with Full Text (via EBSCOhost) and Google search.

RESULTS

Seventeen articles were identified, of which three categories of growth measurements were extracted, comprising weight (weight, WAZ, WHZ, and BMI), height (height/length and HAZ) and head circumference. SHS exposure both pre or postnatally was inversely associated with weight (deficit in weight, risk of underweight, risk of wasting) and height (lower length and risk of stunting) and elevated BMI of children. Furthermore, prenatal SHS exposure was associated with a lower head circumference.

CONCLUSIONS

The current review identified that exposure to SHS may be associated with adverse growth outcomes in children. It is crucial that active smokers, specifically those who live with children or with a pregnant partner, are made aware of the potential effects of SHS exposure on non-smokers. Further assessment of the association between exposure to SHS and other growth outcomes in other age groups is needed.

Nicotine Suppresses the Invasiveness of Human Trophoblasts by Downregulation of CXCL12 Expression through the Alpha-7 Subunit of the Nicotinic Acetylcholine Receptor

Smoke exposure during pregnancy has detrimental effects upon numerous fetal and neonatal outcomes. Nicotine (the main component of tobacco) has been suggested to affect placental development. During placental development, efficient invasion by trophoblasts is required for establishment of the fetus–maternal circulation. In this study we explored the regulation of trophoblast invasion by nicotine. An immortalized first trimester extravillous trophoblast cell line (HTR-8/SVneo cells) was used for all the experiments, which were treated by nicotine, methyllycaconitine, and C-X-C motif chemokine ligand 12 (CXCL12). Total RNA and protein were used to study the expressions of nicotinic acetylcholine receptors (nAChRs), and transwell assay was used to study invasiveness. Changes of RNA expression due to nicotine treatment were detected by RNA sequence. Level of CXCL12 mRNA was verified by quantitative PCR. We showed that HTR-8/SVneo expressed subunits α2–4, α7, α9, β1, and β2 of nAChRs. Nicotine downregulated CXCL12 expression and inhibited trophoblast invasion. Methyllycaconitine, as an antagonist of the α7 homopolymer, blocked the inhibitory effect of nicotine. CXCL12 could rescue the nicotine-induced inhibitory effect on invasion of HTR-8/SVneo cells. These results suggest that the α7 subunit of the nAChR has important roles in modulating trophoblast invasion through CXCL12.

The association between prenatal exposure to environmental tobacco smoke and childhood obesity: a systematic review

OBJECTIVE

The objective of the review was to determine if prenatal exposure to environmental tobacco smoke (ETS) increases the risk of obesity and overweight in children.

INTRODUCTION

Childhood obesity has reached epidemic proportions in many developed countries. This is of great concern as childhood obesity is associated with early onset of chronic diseases such as coronary artery disease, type II diabetes and hypertension in adulthood. Extensive research suggests a multifactorial etiology. These factors include genetic markers, individual lifestyle, social and environmental factors, particularly the interaction between these factors. Among environmental factors, prenatal exposure to ETS has been linked to increased rates of obesity and overweight in childhood.

INCLUSION CRITERIA

This review considered studies on children of women who were non-smokers and who reported exposure to ETS during pregnancy. The exposure of interest was exposure to ETS or second hand smoke during pregnancy, determined by either: i) self-reported maternal exposure; and/or ii) serum cotinine levels. Observational studies such as cohort studies, case control studies, retrospective studies and analytical cross-sectional studies were included. Outcomes of interest were weight, height and body mass index of children from birth up to 18 years.

METHODS

A three-step search strategy was used to search for published and unpublished studies in the English language. No search range (years) was set. Two reviewers assessed the studies for inclusion and methodological quality using the Joanna Briggs Institute System for the Unified Management, Assessment and Review of Information (JBI SUMARI) standardized appraisal instruments. Data was extracted by two people independently and entered into the JBI extraction tool. Extracted data was pooled in a statistical meta-analysis based on a random effects model.

RESULTS

Nineteen studies were included in the review. Eight of the studies were included in the final meta-analysis. Findings suggest that there was an association between prenatal exposure to ETS and childhood obesity (odds ratio [OR]: 1.905, CI: 1.23-2.94), and no association between ETS exposure and overweight (OR: 1.51, CI: 0.49-4.59). The high rates of heterogeneity between studies in both of the meta-analyses determined by the I statistic (97% and 99%, respectively) sanction caution in the interpretation and use of these findings.

CONCLUSIONS

Based on the evidence, childhood obesity is associated with exposure to prenatal ETS, however overweight does not appear to be associated with this type of exposure.

Maternal nicotine dependence is associated with longitudinal increases in child obesogenic eating behaviors

BACKGROUND

Meta-analysis shows that parental cigarette smoking is associated with child obesity.

OBJECTIVES

This study tested for associations between severity of maternal nicotine dependence and longitudinal changes in child eating behavior in archival data analysis.

METHODS

Maternal nicotine dependence was assessed with the Fagerstrom Test for Nicotine Dependence. Child eating behavior was assessed with the Child Eating Behavior Questionnaire when children were ages 4, 6, 8, and 10.

RESULTS

Over and above the influence of child age, child biological sex, and family income-to-needs ratio, more severe maternal nicotine dependence was associated with greater increases in child Food Responsiveness (γ = 0.07, SE_γ  = 0.03, P = .014, 95% CI [0.01, 0.13]) and Emotional Overeating (γ = 0.06, SE_γ  = 0.03, P = .024, 95% CI [0.01, 0.11]) across 6 years.

CONCLUSIONS

Maternal nicotine dependence may be a transdiagnostic risk factor that identifies children at risk for reward-driven, obesogenic eating behavior.

Antenatal exposure to second hand smoke of non-smoking mothers and growth rate of their infants

Objectives

There is limited evidence on the effect of exposure to second hand smoke (SHS) in non-smoking pregnant mothers and infant health. We assessed the effects of maternal antenatal exposure to SHS on infant growth rate, and secondarily, on birth weight, birth length and head circumference at birth.

Methods

In this prospective cohort, 305 mother-infant pairs were studied. Mothers filled out questionnaires about exposure to SHS in pregnancy at the 3^rd trimester of pregnancy. Infant anthropometry was performed at birth, day 7, and months 1, 2, 4, and 6, postnatally. Linear mixed modeling and linear regression were used to calculate growth rates over the first 6 months. The association between SHS-exposure with growth rate and birth sizes was assessed using multivariate linear regression adjusted for confounders, with SHS as both number of cigarettes and as groups (no exposure, SHS < 23 cigarettes, SHS ≥ 23 cigarettes).

Results

Seventy-three mothers were not exposed and 232 were exposed. SHS exposure (per cigarette) was not related to gain in weight, length, head circumference, and weight for length. However, infants born to mothers exposed to ≥ 23 cigarettes/d had lower head circumference gain (-0.32 mm/m, 95% CI -0.60, -0.03) than those born to non-exposed mothers. SHS exposure (per cigarette) was not related to birth weight, length, and head circumference, but exposure to ≥ 23 cigarettes was related to lower head circumference at birth (-11.09 mm, -20.03, -2.16).

Conclusions

Heavy antenatal exposure to SHS in non-smoking mothers results in reduced neonatal head circumference at birth and head circumference gain over the first 6 months of life. Our findings show no clear relations between exposure to SHS during pregnancy and other markers of neonatal growth and birth size.

Differences in Prenatal Tobacco Exposure Patterns among 13 Race/Ethnic Groups in California

Prenatal tobacco exposure is a significant, preventable cause of childhood morbidity, yet little is known about exposure risks for many race/ethnic subpopulations. We studied active smoking and environmental tobacco smoke (ETS) exposure in a population-based cohort of 13 racially/ethnically diverse pregnant women: white, African American, Hispanic, Native American, including nine Asian/Pacific Islander subgroups: Chinese, Japanese, Korean, Filipino, Cambodian, Vietnamese, Laotian, Samoan, and Asian Indians (N = 3329). Using the major nicotine metabolite, cotinine, as an objective biomarker, we analyzed mid-pregnancy serum from prenatal screening banked in 1999–2002 from Southern California in an effort to understand differences in tobacco exposure patterns by race/ethnicity, as well as provide a baseline for future work to assess secular changes and longer-term health outcomes. Prevalence of active smoking (based on age- and race-specific cotinine cutpoints) was highest among African American, Samoan, Native Americans and whites (6.8–14.1%); and lowest among Filipinos, Chinese, Vietnamese and Asian Indians (0.3–1.0%). ETS exposure among non-smokers was highest among African Americans and Samoans, followed by Cambodians, Native Americans, Vietnamese and Koreans, and lowest among Filipinos, Japanese, whites, and Chinese. At least 75% of women had detectable cotinine. While for most groups, levels of active smoking corresponded with levels of ETS, divergent patterns were also found. For example, smoking prevalence among white women was among the highest, but the group’s ETS exposure was low among non-smokers; while Vietnamese women were unlikely to be active smokers, they experienced relatively high ETS exposure. Knowledge of race/ethnic differences may be useful in assessing disparities in health outcomes and creating successful tobacco interventions.

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.

Fetal exposure to maternal active and secondhand smoking with offspring early-life growth in the Healthy Start study

BACKGROUND

Previous studies have modeled the association between fetal exposure to tobacco smoke and body mass index (BMI) growth trajectories, but not the timing of catch-up growth. Research on fetal exposure to maternal secondhand smoking is limited.

OBJECTIVES

To explore the associations between fetal exposure to maternal active and secondhand smoking with body composition at birth and BMI growth trajectories through age 3 years.

METHODS

We followed 630 mother-child pairs enrolled in the Healthy Start cohort through age 3 years. Maternal urinary cotinine was measured at ~ 27 weeks gestation. Neonatal body composition was measured using air displacement plethysmography. Child weight and length/height were abstracted from medical records. Linear regression models examined the association between cotinine categories (no exposure, secondhand smoke, active smoking) with weight, fat mass, fat-free mass, and percent fat mass at birth. A mixed-effects regression model estimated the association between cotinine categories and BMI.

RESULTS

Compared to unexposed offspring, birth weight was significantly lower among offspring born to active smokers (-343-g; 95% CI: -473, -213), but not among offspring of women exposed to secondhand smoke (-47-g; 95% CI: -130, 36). There was no significant difference in the rate of BMI growth over time between offspring of active and secondhand smokers (p = 0.58). Therefore, our final model included a single growth rate parameter for the combined exposure groups of active and secondhand smokers. The rate of BMI growth for the combined exposed group was significantly more rapid (0.27 kg/m² per year; 95% CI: 0.05, 0.69; p < 0.01) than the unexposed.

CONCLUSIONS

Offspring prenatally exposed to maternal active or secondhand smoking experience rapid and similar BMI growth in the first three years of life. Given the long-term consequences of rapid weight gain in early childhood, it is important to encourage pregnant women to quit smoking and limit their exposure to secondhand smoke.

Impact of Smoking Ban on Passive Smoke Exposure in Pregnant Non-Smokers in the Southeastern United States

Prenatal passive smoke exposure raises risk for negative birth outcomes. Legislation regulating public smoking has been shown to impact exposure levels, though fewer studies involving pregnant women have been conducted within the U.S. where bans are inconsistent across regions. This study examined the effect of a ban enacted in the southeastern U.S. on pregnant women's cotinine levels. Additional analyses compared self-reported exposure to cotinine and identified characteristics associated with passive exposure. Pregnant women (N = 851) were recruited prospectively between 2005 and 2011 in North Carolina. Sociodemographic and health data were collected via surveys; maternal blood samples were assayed for cotinine. Among non-active smokers who provided self-report data regarding passive exposure (N = 503), 20% were inconsistent with corresponding cotinine. Among all non-smokers (N = 668), being unmarried, African American, and less educated were each associated with greater passive exposure. Controlling for covariates, mean cotinine was higher prior to the ban compared to after, F(1, 640) = 24.65, p < 0.001. Results suggest that banning smoking in public spaces may reduce passive smoke exposure for non-smoking pregnant women. These data are some of the first to examine the impact of legislation on passive smoke exposure in pregnant women within the U.S. using a biomarker and can inform policy in regions lacking comprehensive smoke-free legislation.

Chemical and non-chemical stressors affecting childhood obesity: a systematic scoping review

Childhood obesity in the United States has doubled over the last three decades and currently affects 17% of children and adolescents. While much research has focused on individual behaviors impacting obesity, little research has emphasized the complex interactions of numerous chemical and non-chemical stressors found in a child's environment and how these interactions affect a child's health and well-being. The objectives of this systematic scoping review were to (1) identify potential chemical stressors in the context of non-chemical stressors that impact childhood obesity; and, (2) summarize our observations for chemical and non-chemical stressors in regards to child-specific environments within a community setting. A review was conducted to identify chemical and non-chemical stressors related to childhood obesity for the childhood life stages ranging from prenatal to adolescence. Stressors were identified and grouped into domains: individual behaviors, family/household behaviors, community stressors, and chemical exposures. Stressors were related to the child and the child's everyday environments and used to characterize child health and well-being. This review suggests that the interactions of chemical and non-chemical stressors are important for understanding a child's overall health and well-being. By considering these relationships, the exposure science research community can better design and implement strategies to reduce childhood obesity.

Association of prenatal passive smoking and metabolic gene polymorphisms with child growth from birth to 3years of age in the Hokkaido Birth Cohort Study on Environment and Children's Health

Although the effects of prenatal passive smoking on birth weight have been reported, the effects of metabolic gene polymorphisms on passive smoking have not been studied. Therefore, we investigated the effects of maternal passive smoking and metabolic gene polymorphisms on child growth up to 3years of age using cotinine as a biomarker. We included 1356 Japanese participants in a prospective cohort between 2003 and 2007 (cotinine levels at the third trimester≤0.21ng/mL and 0.22 to 11.48ng/mL for non-passive and passive smokers, respectively), and measured child outcomes such as weight, length, head circumference, and Kaup index. Additionally, we analyzed cytochrome P450 1A1 (CYP1A1), epoxide hydrolase 1 (EPHX1), and two N-acetyltransferase 2 (NAT2) genotypes using real-time polymerase chain reaction methods. Associations were investigated using multiple regression models. Kaup index gain from birth up to 3years of age was significantly smaller in children born to passive smokers than in those born to non-passive smokers (-0.34kg/m²; 95% confidence interval: -0.67, -0.01). Maternal CYP1A1 genotype was not associated with prenatal passive smoking and Kaup index gain, but was significantly associated with prenatal passive smoking and head circumference gain from birth up to 3years of age (-0.75cm; 95% confidence interval: -1.39, -0.12). Thus, this study suggests that prenatal passive smoking may have potent effects on postnatal growth from birth up to 3years of age. Moreover, children with maternal CYP1A1 genotype may be more susceptible to the effects of prenatal passive smoking.

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.

Is There an Association between Sleeping Patterns and Other Environmental Factors with Obesity and Blood Pressure in an Urban African Population?

Beyond changing dietary patterns, there is a paucity of data to fully explain the high prevalence of obesity and hypertension in urban African populations. The aim of this study was to determine whether other environmental factors (including sleep duration, smoking and physical activity) are related to body anthropometry and blood pressure (BP). Data were collected on 1311 subjects, attending two primary health care clinics in Soweto, South Africa. Questionnaires were used to obtain data on education, employment, exercise, smoking and sleep duration. Anthropometric and BP measurements were taken. Subjects comprised 862 women (mean age 41 ± 16 years and mean BMI 29.9 ± 9.2 kg/m²) and 449 men (38 ± 14 years and 24.8 ± 8.3 kg/m²). In females, ANOVA showed that former smokers had a higher BMI (p<0.001) than current smokers, while exposure to second hand smoking was associated with a lower BMI (p<0.001) in both genders. Regression analyses demonstrated that longer sleep duration was associated with a lower BMI (p<0.05) in older females only, and not in males, whilst in males napping during the day for > 30 minutes was related to a lower BMI (β = -0.04, p<0.01) and waist circumference (β = -0.03, p<0.001). Within males, napping for >30 minutes/day was related to lower systolic (β = -0.02, p<0.05) and lower diastolic BP (β = -0.02, p = 0.05). Longer night time sleep duration was associated with higher diastolic (β = 0.005, p<0.01) and systolic BP (β = 0.003, p<0.05) in females. No health benefits were noted for physical activity. These data suggest that environmental factors rarely collected in African populations are related, in gender-specific ways, to body anthropometry and blood pressure. Further research is required to fully elucidate these associations and how they might be translated into public health programs to combat high levels of obesity and hypertension.

Brief report: are autistic-behaviors in children related to prenatal vitamin use and maternal whole blood folate concentrations?

Prenatal multivitamin/folic acid supplement use may reduce the risk of autism spectrum disorders. We investigated whether 2nd trimester prenatal vitamin use and maternal whole blood folate (WBF) concentrations were associated with Social Responsiveness Scale (SRS) scores at 4-5 years of age in a prospective cohort of 209 mother-child pairs. After confounder adjustment, children born to women taking prenatal vitamins weekly/daily (n = 179) had lower odds of clinically elevated SRS scores (odds ratio 0.26; 95 % confidence interval 0.08, 0.89) than those who rarely/never took them (n = 30). WBF concentrations were not associated with SRS scores. The lack of association between WBF and autistic-behaviors may be due to the timing of biomarker measures relative to critical periods of brain development, confounding, or other modifying factors.

Differences in BMI z-scores between offspring of smoking and nonsmoking mothers: a longitudinal study of German children from birth through 14 years of age

BACKGROUND

Children of mothers who smoked during pregnancy have a lower birth weight but have a higher chance to become overweight during childhood.

OBJECTIVES

We followed children longitudinally to assess the age when higher body mass index (BMI) z-scores became evident in the children of mothers who smoked during pregnancy, and to evaluate the trajectory of changes until adolescence.

METHODS

We pooled data from two German cohort studies that included repeated anthropometric measurements until 14 years of age and information on smoking during pregnancy and other risk factors for overweight. We used longitudinal quantile regression to estimate age- and sex-specific associations between maternal smoking and the 10th, 25th, 50th, 75th, and 90th quantiles of the BMI z-score distribution in study participants from birth through 14 years of age, adjusted for potential confounders. We used additive mixed models to estimate associations with mean BMI z-scores.

RESULTS

Mean and median (50th quantile) BMI z-scores at birth were smaller in the children of mothers who smoked during pregnancy compared with children of nonsmoking mothers, but BMI z-scores were significantly associated with maternal smoking beginning at the age of 4-5 years, and differences increased over time. For example, the difference in the median BMI z-score between the daughters of smokers versus nonsmokers was 0.12 (95% CI: 0.01, 0.21) at 5 years, and 0.30 (95% CI: 0.08, 0.39) at 14 years of age. For lower BMI z-score quantiles, the association with smoking was more pronounced in girls, whereas in boys the association was more pronounced for higher BMI z-score quantiles.

CONCLUSIONS

A clear difference in BMI z-score (mean and median) between children of smoking and nonsmoking mothers emerged at 4-5 years of age. The shape and size of age-specific effect estimates for maternal smoking during pregnancy varied by age and sex across the BMI z-score distribution.

Serum cotinine and whole blood folate concentrations in pregnancy

PURPOSE

Prenatal tobacco smoke exposure may be associated with low maternal folate levels that increase the risk of adverse infant and child health outcomes by reducing folate availability during fetal development.

METHODS

Using data from the Health Outcomes and Measures of the Environment Study, we examined the relationship between secondhand or active tobacco smoke exposure and whole blood folate concentrations in pregnant women from Cincinnati, Ohio (n = 362) at approximately 16-week gestation. We used multivariable linear regression to examine the association between continuous or categorical serum cotinine levels and whole blood folate levels, adjusting for sociodemographic, dietary, and perinatal variables.

RESULTS

After adjustment for potential confounders, an interquartile range increases in serum cotinine concentration (0.012-0.224 ng/mL) was suggestively associated with decreased whole blood folate levels (β, -23 nmol/L; 95% confidence interval (CI), -49, 3; P value = .08). Compared with unexposed women, reductions in mean whole blood folate were observed among active smokers (β, -94, 95% CI, 195, 6 nmol/L; P value = .40); smaller reductions were observed among women with secondhand exposure (β, 26; CI, 84, 32 nmol/L; P value = .07).

CONCLUSIONS

Consistent with prior studies, active smoking was associated with reduced whole blood folate levels among these pregnant women. Secondhand tobacco smoke exposures were associated with small and imprecise reductions in whole blood folate levels.

Effect of tobacco smoke exposure during pregnancy and preschool age on growth from birth to adolescence: a cohort study

BACKGROUND

There is strong evidence of an association between maternal smoking during pregnancy and restriction of intrauterine growth, but the effects of this exposure on postnatal linear growth are not well defined. Furthermore, few studies have investigated the role of tobacco smoke exposure also after pregnancy on linear growth until adolescence. In this study we investigated the effect of maternal smoking exposure during pregnancy and preschool age on linear growth from birth to adolescence.

METHODS

We evaluated a cohort of children born between 1994 and 1999 in Cuiabá, Brazil, who attended primary health clinics for vaccination between the years 1999 and 2000 (at preschool age) and followed-up after approximately ten years. Individuals were located in public and private schools throughout the country using the national school census. Height/length was measured, and length at birth was collected at maternity departments. Stature in childhood and adolescence was assessed using the height-for-age index sex-specific expressed as z-score from curves published by the World Health Organization. Linear mixed effects models were used to estimate the association between exposure to maternal smoking, during pregnancy and preschool age, and height of children assessed at birth, preschool and school age, adjusted for age of the children.

RESULTS

We evaluated 2405 children in 1999-2000, length at birth was obtained from 2394 (99.5%), and 1716 at follow-up (71.4% of baseline), 50.7% of the adolescents were male. The z-score of height-for-age was lower among adolescents exposed to maternal smoking both during pregnancy and childhood (p < 0.01). Adjusting for age, sex, maternal height, maternal schooling, socioeconomic position at preschool age, and breastfeeding, children exposed to maternal smoking both during pregnancy and preschool age showed persistent lower height-for-age since birth to adolescence (coefficient: -0.32, p < 0.001) compared to non-exposed. Paternal smoking at preschool age was not associated with growth after adjustment for confounders.

CONCLUSION

Exposure to maternal smoking not only during pregnancy, but also at early childhood, showed long-term negative effect on height of children until adolescence.

Families at risk: home and car smoking among pregnant women attending a low-income, urban prenatal clinic

INTRODUCTION

Secondhand smoke exposure (SHSe) has been identified as a distinct risk factor for adverse obstetric and gynecological outcomes. This study examined the prevalence of SHSe reduction practices (i.e., home and car smoking bans) among pregnant women in a large U.S. prenatal clinic serving low-income women.

METHODS

Pregnant women (N = 820) attending a university-based, urban prenatal clinic in Houston, Texas, completed a prenatal questionnaire assessing bans on household and car smoking and a qualitative urine cotinine test as part of usual care. Data were collected from April 2011 to August 2012.

RESULTS

Nearly one-third (n = 257) of the sample reported at least 1 smoker living in the home. About a quarter of the women in the full sample did not have a total smoking ban in their home and car. Within smoking households, 44% of the pregnant women reported smoking, 56% reported smoking by another household member, and in 26% of smoking households both the pregnant woman and at least one other person were smoking. Only 43% of women with a household smoker reported a total ban on smoking, with higher rates among Hispanic women. Smoking bans were less common when the pregnant women smoked, when more than 1 smoker resided in the home, and when pregnant with her first child.

CONCLUSIONS

SHSe among low-income pregnant women is high, and interventions to raise awareness and increase the establishment of smoking bans in homes and cars are warranted.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

In utero exposure to benzo[a]pyrene increases adiposity and causes hepatic steatosis in female mice, and glutathione deficiency is protective

Polycyclic aromatic hydrocarbons (PAHs), including benzo[a]pyrene (BaP), are ubiquitous environmental pollutants found in tobacco smoke, air pollution, and grilled foods. Reactive metabolites and reactive oxygen species generated during PAH metabolism are detoxified by reactions involving glutathione (GSH). Early life exposures to tobacco smoke and air pollution have been linked to increased risk of obesity and metabolic syndrome. We investigated the independent and interactive effects of prenatal exposure to BaP and GSH deficiency due to deletion of the modifier subunit of glutamate cysteine ligase (Gclm), the rate-limiting enzyme in GSH synthesis, on adiposity and hepatic steatosis in adult female F1 offspring. We mated Gclm(+/-) dams with Gclm(+/-) males and treated the pregnant dams with 0, 2, or 10mg/kg/day BaP in sesame oil by oral gavage daily from gestational day 7 through 16. We analyzed metabolic endpoints in female Gclm(-/-) and Gclm(+/+) littermate F1 offspring. Prenatal BaP exposure significantly increased visceral adipose tissue weight, weight gain between 3 weeks and 7.5 months of age, hepatic lipid content measured by oil red O staining, and hepatic fatty acid beta-oxidation gene expression in Gclm(+/+), but not in Gclm(-/-), female offspring. Hepatic expression of lipid biosynthesis and antioxidant genes were decreased and increased, respectively, in Gclm(-/-) mice. Our results suggest that reported effects of pre- and peri-natal air pollution and tobacco smoke exposure on obesity may be mediated in part by PAHs. GSH deficiency is protective against the metabolic effects of prenatal BaP exposure.

Evaluation of the impact of maternal smoking on ultrasound and endocrinological markers of first trimester placentation

OBJECTIVES

To study the effect of maternal smoking on 2D ultrasound measurements and maternal serum (MS) levels of endocrinologic markers of placentation.

STUDY DESIGN

Prospective population-based cohort study of 32 smokers and 96 non-smoking controls with a normal pregnancy outcome.

MAIN OUTCOME MEASURES

Placental thickness and 2D-volume and MS levels of pregnancy-associated plasma protein A (PAPP-A) and free-beta human chorionic gonadotrophin (fβhCG) at 11-13(+6)weeks of gestation and mid-trimester MS α-fetoprotein (AFP), unconjugated estriol (uE3) and inhibin A levels.

RESULTS

The MS levels of fβhCG and PAPP-A were significantly (P < 0.01 and P < 0.001, respectively) lower in the serum and the level of inhibin A significantly (P < 0.001) higher in the smokers than in controls. There was no significant difference for the MSAFP, MSuE3 placental thickness, basal plate surface and volume between the groups.

CONCLUSION

The placental morphological alterations secondary to maternal smoking are mainly at the level of the villous trophoblast and are not associated with changes in the placental size or utero-placental interface during the first trimester of pregnancy.

Endocrine effects of tobacco smoke exposure during lactation in weaned and adult male offspring

Children from pregnant smokers show more susceptibility to develop obesity in adult life. Previously, we failed to demonstrate a program for obesity in rat offspring only when the mothers were exposed to tobacco smoke during lactation. Here, we studied the short- and long-term effects of smoke exposure (SE) to both dams and their pups during lactation on endocrine and metabolic parameters. For this, we designed an experimental model where nursing rats and their pups were divided into two groups: SE group, exposed to smoke in a cigarette smoking machine (four times/day, from the third to the 21st day of lactation), and group, exposed to filtered air. Pups were killed at 21 and 180 days. At weaning, SE pups showed lower body weight (7%), length (5%), retroperitoneal fat mass (59%), visceral adipocyte area (60%), and higher subcutaneous adipocyte area (95%) with hypoinsulinemia (-29%), hyperthyroxinemia (59%), hypercorticosteronemia (60%), and higher adrenal catecholamine content (+58%). In adulthood, SE offspring showed higher food intake (+10%), body total fat mass (+50%), visceral fat mass (retroperitoneal: 55%; mesenteric: 67%; and epididymal: 55%), and lower subcutaneous adipocyte area (24%) with higher serum glucose (11%), leptin (85%), adiponectin (1.4-fold increase), total triiodothyronine (71%), free thyroxine (57%), TSH (36%), triglycerides (65%), VLDL cholesterol (+66%), and HDL cholesterol (91%) levels and lower corticosteronemia (41%) and adrenal catecholamine content (57%). Our present findings suggest that tobacco SE to both dams and their pups during lactation causes malnutrition in early life that programs for obesity and hormonal and metabolic disturbances in adulthood, only if the pups are submitted to the same smoke environment as the mother.

Evaluation of the association between maternal smoking, childhood obesity, and metabolic disorders: a national toxicology program workshop review

BACKGROUND

An emerging literature suggests that environmental chemicals may play a role in the development of childhood obesity and metabolic disorders, especially when exposure occurs early in life.

OBJECTIVE

Here we assess the association between these health outcomes and exposure to maternal smoking during pregnancy as part of a broader effort to develop a research agenda to better understand the role of environmental chemicals as potential risk factors for obesity and metabolic disorders.

METHODS

PubMed was searched up to 8 March 2012 for epidemiological and experimental animal studies related to maternal smoking or nicotine exposure during pregnancy and childhood obesity or metabolic disorders at any age. A total of 101 studies-83 in humans and 18 in animals-were identified as the primary literature.

DISCUSSION

Current epidemiological data support a positive association between maternal smoking and increased risk of obesity or overweight in offspring. The data strongly suggest a causal relation, although the possibility that the association is attributable to unmeasured residual confounding cannot be completely ruled out. This conclusion is supported by findings from laboratory animals exposed to nicotine during development. The existing literature on human exposures does not support an association between maternal smoking during pregnancy and type 1 diabetes in offspring. Too few human studies have assessed outcomes related to type 2 diabetes or metabolic syndrome to reach conclusions based on patterns of findings. There may be a number of mechanistic pathways important for the development of aberrant metabolic outcomes following perinatal exposure to cigarette smoke, which remain largely unexplored.

CONCLUSIONS

From a toxicological perspective, the linkages between maternal smoking during pregnancy and childhood overweight/obesity provide proof-of-concept of how early-life exposure to an environmental toxicant can be a risk factor for childhood obesity.

Secondhand tobacco smoke exposure is associated with prolactin but not thyroid stimulating hormone among nonsmoking women seeking in vitro fertilization

Prolactin (PRL) and thyroid stimulating hormone (TSH) serve important roles in the reproductive and other systems. Active smoking is associated with changes in PRL and TSH secretion, but the relationship between secondhand tobacco smoke (STS) exposure and these hormones is unclear. We measured PRL and TSH in serum as well as cotinine in follicular fluid (to estimate STS exposure) among 314 nonsmoking women undergoing in vitro fertilization treatment. We observed a significant increase in PRL concentrations (p=0.03) among STS-exposed nonsmokers compared to unexposed nonsmokers. There was no significant difference in TSH concentration (p>0.4) among those exposed to STS compared to those who were unexposed. STS exposure is associated with an increase in circulating PRL but not TSH levels. Future studies are needed to confirm our results, identify biological mechanisms involved, and better understand the potential clinical and public health implications.

Associations of prenatal exposure to organophosphate pesticide metabolites with gestational age and birth weight

BACKGROUND

Prenatal exposure to organophosphate (OP) insecticides, a widely used class of pesticides, may be associated with decreased gestational age and lower birth weight. Single nucleotide polymorphisms in paroxanase (PON1) enzyme genotypes may modify the relationships between OP exposure and perinatal outcomes.

OBJECTIVE

We examined the relationship of prenatal OP insecticide exposure, measured using urinary dialkyl phosphate (DAP) metabolite concentrations, with gestational age and birth weight.

METHODS

We measured the concentrations of six nonspecific DAP metabolites of OP insecticides in two maternal spot urine samples collected in a prospective birth cohort. We performed multivariable regression to examine associations between the sum of six DAP concentrations (ΣDAP) with gestational age and birth weight. We also examined whether these associations differed according to infant PON1(192) and PON1(-108) genotypes.

RESULTS

Among 306 mother-infant dyads, a 10-fold increase in ΣDAP concentrations was associated with a decrease in covariate-adjusted gestational age [-0.5 weeks; 95% confidence interval (CI): -0.8, -0.1] and birth weight (-151 g; CI: -287, -16); the decrements in birth weight were attenuated after adjusting for gestational age. The relationship between ΣDAP concentrations and gestational age was stronger for white (-0.7 weeks; CI: -1.1, -0.3) than for black (-0.1 weeks; 95% CI: -0.9, 0.6) newborns. In contrast, there was a greater decrease in birth weight with increasing urinary ΣDAP concentrations for black (-188 g; CI: -395, 19) than for white (-118 g; CI: -296, 60) newborns. Decrements in birth weight and gestational age associated with ΣDAP concentrations were greatest among infants with PON1(192QR) and PON(-108CT) genotypes.

CONCLUSIONS

Prenatal urinary ΣDAP concentrations were associated with shortened gestation and reduced birth weight in this cohort, but the effects differed by race/ethnicity and PON1(192/108) genotypes.

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.

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.

Impact of early-life bisphenol A exposure on behavior and executive function in children

OBJECTIVES

To estimate the impact of gestational and childhood bisphenol A (BPA) exposures on behavior and executive function at 3 years of age and to determine whether child gender modified those associations.

METHODS

We used a prospective birth cohort of 244 mothers and their 3-year-old children from the greater Cincinnati, Ohio, area. We characterized gestational and childhood BPA exposures by using the mean BPA concentrations in maternal (16 and 26 weeks of gestation and birth) and child (1, 2, and 3 years of age) urine samples, respectively. Behavior and executive function were measured by using the Behavior Assessment System for Children 2 (BASC-2) and the Behavior Rating Inventory of Executive Function-Preschool (BRIEF-P).

RESULTS

BPA was detected in >97% of the gestational (median: 2.0 μg/L) and childhood (median: 4.1 μg/L) urine samples. With adjustment for confounders, each 10-fold increase in gestational BPA concentrations was associated with more anxious and depressed behavior on the BASC-2 and poorer emotional control and inhibition on the BRIEF-P. The magnitude of the gestational BPA associations differed according to child gender; BASC-2 and BRIEF-P scores increased 9 to 12 points among girls, but changes were null or negative among boys. Associations between childhood BPA exposure and neurobehavior were largely null and not modified by child gender.

CONCLUSIONS

In this study, gestational BPA exposure affected behavioral and emotional regulation domains at 3 years of age, especially among girls. Clinicians may advise concerned patients to reduce their exposure to certain consumer products, but the benefits of such reductions are unclear.