Prenatal tobacco exposure associations with physical health and neurodevelopment in the ABCD cohort

OBJECTIVE

To investigate the strength and reproducibility of the teratogenic impact of prenatal tobacco exposure (PTE) on child physical health and neurodevelopmental outcomes, in the context of intersecting sociodemographic and other prenatal correlates, and test if early postnatal health mediates PTE associations with childhood outcomes.

METHOD

Among 9-10-year-olds (N = 8,803) in the Adolescent Brain Cognitive Development Study, linear mixed-effect models tested PTE associations with birth and childhood outcomes of physical health, cognitive performance, and brain structure, controlling for confounding sociodemographic and prenatal health correlates. Mediation analysis tested the extent to which health at birth explained the associations between PTE and childhood outcomes.

RESULTS

PTE was reported by 12% of mothers (8% [n = 738] pre-knowledge of pregnancy only, and 4% [n = 361] pre- and post-knowledge of pregnancy). PTE was highest for children with a risk for passive smoke exposure. Overall, children with any PTE had shorter breastfeeding durations than those without PTE, and PTE following knowledge of pregnancy was associated with being small for gestational age having lower birth weight, and obesity and lower cortical volume and surface area in childhood. Among children from high-parent education households, any PTE was related to lower cognitive performance, which was partially mediated by duration of breastfeeding.

CONCLUSIONS

PTE was linked to poorer health indicators at birth and neurodevelopmental outcomes at age 9-10 years in a large community cohort, independent of sociodemographic factors. Efficacious interventions for smoking-cessation during pregnancy are still needed and should incorporate support for breastfeeding to promote healthier development. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Demystifying the impact of prenatal tobacco exposure on the placental immune microenvironment: Avoiding the tragedy of mending the fold after death

Prenatal tobacco exposure (PTE) correlates significantly with a surge in adverse pregnancy outcomes, yet its pathological mechanisms remain partially unexplored. This study aims to meticulously examine the repercussions of PTE on placental immune landscapes, employing a coordinated research methodology encompassing bioinformatics, machine learning and animal studies. Concurrently, it aims to screen biomarkers and potential compounds that could sensitively indicate and mitigate placental immune disorders. In the course of this research, two gene expression omnibus (GEO) microarrays, namely GSE27272 and GSE7434, were included. Gene set enrichment analysis (GSEA) and immune enrichment investigations on differentially expressed genes (DEGs) indicated that PTE might perturb numerous innate or adaptive immune-related biological processes. A cohort of 52 immune-associated DEGs was acquired by cross-referencing the DEGs with gene sets derived from the ImmPort database. A protein-protein interaction (PPI) network was subsequently established, from which 10 hub genes were extracted using the maximal clique centrality (MCC) algorithm (JUN, NPY, SST, FLT4, FGF13, HBEGF, NR0B2, AREG, NR1I2, SEMA5B). Moreover, we substantiated the elevated affinity of tobacco reproductive toxicants, specifically nicotine and nitrosamine, with hub genes through molecular docking (JUN, FGF13 and NR1I2). This suggested that these genes could potentially serve as crucial loci for tobacco's influence on the placental immune microenvironment. To further elucidate the immune microenvironment landscape, consistent clustering analysis was conducted, yielding three subtypes, where the abundance of follicular helper T cells (p < 0.05) in subtype A, M2 macrophages (p < 0.01), neutrophils (p < 0.05) in subtype B and CD8+ T cells (p < 0.05), resting NK cells (p < 0.05), M2 macrophages (p < 0.05) in subtype C were significantly different from the control group. Additionally, three pivotal modules, designated as red, blue and green, were identified, each bearing a close association with differentially infiltrated immunocytes, as discerned by the weighted gene co-expression network analysis (WGCNA). Functional enrichment analysis was subsequently conducted on these modules. To further probe into the mechanisms by which immune-associated DEGs are implicated in intercellular communication, 20 genes serving as ligands or receptors and connected to differentially infiltrating immunocytes were isolated. Employing a variety of machine learning techniques, including one-way logistic regression, LASSO regression, random forest and artificial neural networks, we screened 11 signature genes from the intersection of immune-associated DEGs and secretory protein-encoding genes derived from the Human Protein Atlas. Notably, CCL18 and IFNA4 emerged as prospective peripheral blood markers capable of identifying PTE-induced immune disorders. These markers demonstrated impressive predictive power, as indicated by the area under the curve (AUC) of 0.713 (0.548-0.857) and 0.780 (0.618-0.914), respectively. Furthermore, we predicted 34 potential compounds, including cyclosporine, oestrogen and so on, which may engage with hub genes and attenuate immune disorders instigated by PTE. The diagnostic performance of these biomarkers, alongside the interventional effect of cyclosporine, was further corroborated in animal studies via ELISA, Western blot and immunofluorescence assays. In summary, this study identifies a disturbance in the placental immune landscape, a secondary effect of PTE, which may underlie multiple pregnancy complications. Importantly, our research contributes to the noninvasive and timely detection of PTE-induced placental immune disorders, while also offering innovative therapeutic strategies for their treatment.

Contextualizing the impact of prenatal alcohol and tobacco exposure on neurodevelopment in a South African birth cohort: an analysis from the socioecological perspective

Background

Alcohol and tobacco are known teratogens. Historically, more severe prenatal alcohol exposure (PAE) and prenatal tobacco exposure (PTE) have been examined as the principal predictor of neurodevelopmental alterations, with little incorporation of lower doses or ecological contextual factors that can also impact neurodevelopment, such as socioeconomic resources (SER) or adverse childhood experiences (ACEs). Here, a novel analytical approach informed by a socio-ecological perspective was used to examine the associations between SER, PAE and/or PTE, and ACEs, and their effects on neurodevelopment.

Methods

N = 313 mother-child dyads were recruited from a prospective birth cohort with maternal report of PAE and PTE, and cross-sectional structural brain neuroimaging of child acquired via 3T scanner at ages 8-11 years. In utero SER was measured by maternal education, household income, and home utility availability. The child's ACEs were measured by self-report assisted by the researcher. PAE was grouped into early exposure (<12 weeks), continued exposure (>=12 weeks), and no exposure controls. PTE was grouped into exposed and non-exposed controls.

Results

Greater access to SER during pregnancy was associated with fewer ACEs (maternal education: β = -0.293,p = 0.01; phone access: β = -0.968,p = 0.05). PTE partially mediated the association between SER and ACEs, where greater SER reduced the likelihood of PTE, which was positively associated with ACEs (β = 1.110,p = 0.01). SER was associated with alterations in superior frontal (β = -1336.036, q = 0.046), lateral orbitofrontal (β = -513.865, q = 0.046), caudal anterior cingulate volumes (β = -222.982, q = 0.046), with access to phone negatively associated with all three brain volumes. Access to water was positively associated with superior frontal volume (β=1569.527, q = 0.013). PTE was associated with smaller volumes of lateral orbitofrontal (β = -331.000, q = 0.033) and nucleus accumbens regions (β = -34.800, q = 0.033).

Conclusion

Research on neurodevelopment following community-levels of PAE and PTE should more regularly consider the ecological context to accelerate understanding of teratogenic outcomes. Further research is needed to replicate this novel conceptual approach with varying PAE and PTE patterns, to disentangle the interplay between dose, community-level and individual-level risk factors on neurodevelopment.

Examining the latent factor structure of a hypothetical cigarette purchase task among pregnant women

The cigarette purchase task (CPT) is a valid behavioral-economic measure of demand that has smokers estimate hypothetical cigarette consumption under a range of escalating prices. The task involves no experimenter exposure of participants to smoking. CPT demand is measured in terms of five indices: intensity (cigarettes consumed at $0), Omax (largest expenditure), Pmax (price associated with peak expenditure), breakpoint (the first price at which consumption is 0), and elasticity (rate at which consumption changes as a function of increasing price). Out of concern for collinearity, prior studies investigated a more parsimonious CPT latent-factor structure for these derived indices consisting of two factors. The present study examined whether the same two latent-factor solutions extend to pregnant women who smoke. Six hundred sixty-five women completed the CPT as part of recruitment for a clinical trial examining the efficacy of a remote contingency-management intervention to promote smoking cessation during pregnancy. Factor analysis confirmed a two-factor solution to the CPT accounting for 87% of the variance in the five indices with demand intensity and Omax loading onto amplitude and Omax, Pmax, breakpoint, and elasticity loading onto persistence. Backward elimination regression revealed a significant negative relationship between amplitude and persistence (i.e., lower amplitude and persistence scores predicted a higher likelihood of making at least one quit attempt upon learning of pregnancy). These results further support the utility of the CPT for experimentally examining individual differences in smoking among pregnant women in an efficient and ethical manner that does not involve exposing them to cigarette smoke. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Executive functioning, behavioural, emotional, and cognitive difficulties in school-aged children prenatally exposed to methadone

Aim

The aim of this study was to examine executive function and emotional and behavioural difficulties of children aged between 8 and 10 years who had been prenatally exposed to methadone, compared to non-exposed peers.

Methods

Prospective study: third follow-up of an original cohort of 153 children born to methadone-maintained opioid-dependent mothers 2008-2010: previous investigations were at 1-3 days and at 6-7 months of age. Carers completed the Strength and Difficulties Questionnaire (SDQ) and the Behaviour Rating Inventory of Executive Function, Second Edition (BRIEF®2). Results were compared between exposed and non-exposed groups.

Results

Carers of 33 of 144 traceable children completed the measures. SDQ responses showed no group differences on subscales of emotional symptoms, conduct problems, or peer relationship problems. A marginally higher proportion of exposed children had a high or very high hyperactivity subscale score. Exposed children scored significantly higher on BRIEF®2 behavioural, emotional, and cognitive regulation indices, and on the global executive composite. After controlling for potentially confounding higher reported maternal tobacco use in the exposed group via regression modelling, the effect of methadone exposure reduced.

Interpretation

This study supports evidence that methadone exposure in utero is associated with adverse neurodevelopmental outcomes in childhood. Challenges in studying this population include difficulties with long-term follow-up and controlling for potentially confounding factors. Further investigation of the safety of methadone and other opioids in pregnancy must include consideration of maternal tobacco use.

Within- and between-family transactions of maternal depression and child engagement in the first 2 years of life: Role of prenatal maternal risk and tobacco use

BACKGROUND

This study examined transactional associations among maternal depression, maternal sensitivity, and child engagement in the context of a low-income, diverse sample with maternal cigarette smoking during pregnancy (MSDP) as a moderator of these transactions.

METHODS

A random-intercept cross-lagged panel model was used to investigate within- and between-family variability from infancy to toddlerhood. The sample included 247 mother-child dyads (47% girls; 51% African-American; 178 MSDP, 69 non-MSDP). Assessments were conducted once during each trimester of pregnancy and at 2, 9, 16, and 24 months of child ages.

RESULTS

Between-family associations revealed that children exposed to higher levels of sensitive parenting across time had higher behavioral engagement from infancy to toddlerhood. At the within-family level, increased sensitive parenting at 9 months was predictive of increased child engagement at 16 months which in turn predicted increases in sensitive parenting at 24 months. Increased maternal depression was concurrently associated with lower maternal sensitivity at 2 months and lower child engagement at 16 months. Contrary to hypotheses, changes in maternal depression were not associated to changes in parenting or child engagement. These associations did not vary between prenatally smoking and nonsmoking mothers. However, there was significantly higher stability in maternal depression across time among nonsmoking mothers compared to those in the MSDP group. Additionally, increased maternal depression was related to lower-than-expected child engagement at 9 months only for the nonsmoking group.

CONCLUSIONS

Results highlight transactional processes at the within-family level and the importance of timing for parent and child effects on transactional processes.

Maternal tobacco exposure during pregnancy and allergic rhinitis in offspring: A systematic review and meta-analysis

BACKGROUND

Maternal tobacco exposure during pregnancy is known to cause a potential hazard to the offspring's health. So far, published studies have shown no consistent results with whether tobacco exposure in utero is causally linked to the development of allergic rhinitis in offspring. The aim of this study was to comprehensively evaluate the association between maternal tobacco exposure during pregnancy and allergic rhinitis in offspring by meta-analysis and to provide reference for clinical work.

METHODS

Literatures were searched in CNKI, Wanfang Data, VIP, SinoMed, PubMed, Web of science and Embase up to September 30,2020. Screening, inclusion, quality assessment, data extraction and data analysis of the literatures were conducted. Meta-analysis was performed with Revman 5.3 and State15.1 software. Odds ratio (OR) and 95%CI were used as observation indicators.

RESULTS

We had retrieved 16 articles with 22 independent datasets and 11,49,879 sample size. When all the studies were analyzed together, the results showed that maternal smoking exposure during pregnancy would increase the risk of allergic rhinitis in offspring (OR = 1.13, 95%CI:1.02-1.26), especially maternal passive smoking during pregnancy (OR = 1.39, 95%CI:1.05-1.84). But subgroup analysis showed that maternal active smoking during pregnancy was only significantly associated with offspring allergic rhinitis in cross-sectional studies (OR = 1.24, 95%CI:1.07-1.45) and study done in America study (OR = 1.22, 95%CI:1.05-1.42).

CONCLUSIONS

Tobacco exposure during pregnancy could increase the risk of allergic rhinitis in offspring. The importance of avoiding prenatal tobacco exposure should be emphasized more for the health of next generation in the public.

Prenatal Exposure to Alcohol, Tobacco, and Coffee: Associated Congenital Complications and Adverse Birth Outcomes

A few studies to date have examined the association between prenatal exposure to alcohol, tobacco, and coffee, and congenital complications/adverse birth outcomes among South Korean populations. Thus, this study analyzed the data of 1675 Korean women with birth experience within the last 3 years for pregnancy-related health and nutritional behaviors and relative outcomes. During their pregnancies, 11.58% of the study population consumed alcohol at least once, 1.43% drank throughout all three trimesters, 1.13% smoked, 25.43% were exposed to secondhand smoking, and 28.18% consumed 3 coffees or more every day. Prenatal alcohol exposure was associated with 11.24 times increased risk of birth defects/disabilities [Odds Ratio (OR): 11.24, 95% Confidence Interval (CI) 1.07-117.86] and 10.66 times increased risk of inherited metabolic diseases (OR: 10.66, 95% CI: 1.08-104.82). Prenatal secondhand smoke exposure (OR: 1.62, 95% CI: 1.01-2.62) and coffee consumption (OR: 1.92, 95% CI: 1.22-3.03) was associated with increased risk of low birth weight. Such results were in alignment with that of previous studies and confirmed that prenatal alcohol, tobacco, and coffee exposure can have detrimental neonatal and maternal consequences.

Increased Risk for Cerebral Hypoxia During Immediate Neonatal Transition After Birth in Term Neonates Delivered by Caesarean Section With Prenatal Tobacco Exposure

Introduction: Maternal tobacco smoking during pregnancy is a global health problem leading to an increased risk for fetal and neonatal morbidities. So far, there are no data of the potential impact of maternal smoking during pregnancy on the most vulnerable period after birth - the immediate postnatal transition. The aim of the present study was therefore, to compare cerebral oxygenation during immediate postnatal transition in term neonates with and without prenatal tobacco exposure. Methods: Included in this post-hoc analysis were healthy term neonates, with measurements of cerebral oxygenation (INVOS 5100C) during the first 15 min after birth, and for whom information on maternal smoking behavior during pregnancy was available. Neonates with prenatal tobacco exposure (smoking group) were matched 1:1 according to gestational age (±1 week), birth weight (±100 grams) and hematocrit (±5 %) to neonates without (non-smoking group). Cerebral regional tissue oxygen saturation (crSO₂), cerebral fractional tissue oxygen extraction (cFTOE), arterial oxygen saturation (SpO₂) and heart rate (HR) within the first 15 min after birth were compared between the two groups. Results: Twelve neonates in the smoking group with a median (IQR) gestational age of 39.1 (38.8-39.3) weeks and a birth weight of 3,155 (2,970-3,472) grams were compared to 12 neonates in the non-smoking group with 39.1 (38.7-39.2) weeks and 3,134 (2,963-3,465) grams. In the smoking group, crSO₂ was significantly lower and cFTOE significantly higher until min 5 after birth. HR was significantly higher in the smoking group in min 3 after birth. Beyond this period, there were no significant differences between the two groups. Conclusion: Cerebral oxygenation within the first 5 min after birth was compromised in neonates with prenatal tobacco exposure. This observation suggests a higher risk for cerebral hypoxia immediately after birth due to fetal tobacco exposure.

Preconception and prenatal cannabis use and the risk of behavioural and emotional problems in the offspring; a multi-informant prospective longitudinal study

BACKGROUND

Studies of the long-term consequences of maternal cannabis use on child development beyond the neonatal period are sparse. In the current study, we use a multi-information approach to assess the association of prenatal cannabis exposure and child behavioural and emotional functioning. To explore the possible causal nature of the association, we investigated whether maternal tobacco and paternal cannabis use during pregnancy were also associated with child problems.

METHODS

The study population included children of a population-based birth cohort in The Netherlands (n = 5903). Information on parental cannabis use was collected using questionnaires; urine of mothers was analysed for the presence of cannabis metabolites. Child behavioural and emotional problems at approximately 7-10 years were measured using validated teacher-, child- and mother-reports.

RESULTS

Our findings show associations of maternal cannabis use during pregnancy with offspring externalising problems (B = 0.53; 95% CI: 0.29-0.77), but not with internalising problems (B = -0.10; 95% CI: -0.31-0.11). However, maternal cannabis use before pregnancy was also associated with offspring externalising problems (B = 0.27; 95% CI: 0.02-0.52). Further, cannabis use by the father was associated with child externalising problems (B = 0.36; 95% CI: 0.22-0.49) but not internalising problems.

CONCLUSIONS

Prenatal exposure to maternal cannabis use is specifically associated with offspring behavioural problems, but not emotional problems. This association is probably not due to an effect of intrauterine cannabis exposure on fetal development, because both maternal and paternal cannabis exposure during pregnancy were related to offspring externalising problems. Our findings suggest that the association can be explained through residual confounding, most likely through shared genetic vulnerabilities for parental cannabis use and offspring behavioural problems.

Does early maternal responsiveness buffer prenatal tobacco exposure effects on young children's behavioral disinhibition?

Children with prenatal tobacco exposure (PTE) exhibit early self-regulatory impairments, reflecting a life-course persistent propensity toward behavioral disinhibition. Previously, we demonstrated the protective role of parental responsiveness for reducing the risk of exposure-related disruptive behavior in adolescence. Here, we expanded this line of inquiry, examining whether responsiveness moderates the relation of PTE to a broader set of behavioral disinhibition features in early childhood and testing alternative diathesis-stress versus differential susceptibility explanatory models. PTE was assessed prospectively using interviews and bioassays in the Midwestern Infant Development Study (MIDS). Mother-child dyads (N = 276) were re-assessed at approximately 5 years of age in a preschool follow-up. We quantified maternal responsiveness and child behavioral disinhibition using a combination of directly observed activities in the lab and developmentally sensitive questionnaires. Results supported a diathesis-stress pattern. Children with PTE and less responsive mothers showed increased disruptive behavior and lower effortful control compared with children without PTE. In contrast, exposed children with more responsive mothers had self-regulatory profiles similar to their non-exposed peers. We did not observe sex differences. Findings provide greater specification of the protective role of maternal responsiveness for self-regulation in children with PTE and help clarify mechanisms that may underscore trajectories of exposure-related behavioral disinhibition.

Prenatal exposure to tobacco and marijuana and child autonomic regulation and reactivity: An analysis of indirect pathways via maternal psychopathology and parenting

We examined a conceptual model for the associations of prenatal exposure to tobacco (PTE) and marijuana with child reactivity/regulation at 16 months of age. We hypothesized that PTE would be associated with autonomic reactivity and regulation that these associations would be indirect via maternal anger/hostility, depression/stress, or harsh parenting assessed at 2 months and that these effects would be most pronounced among children exposed to both tobacco and marijuana (PTME). Participants were 247 dyads (81 PTE, 97 PTME, and 69 nonexposed) who were followed up at 2 (N = 247) and 16 months (N = 238) of child age. Results from model testing indicated an indirect association between PTME and autonomic functioning during the second year of life, which was mediated by harsh parenting during caregiver-infant interactions. This study fills an important gap in the literature on PTE, PTME, and autonomic regulation during the toddler years, highlighting the role of maternal parenting as important intervening variables.

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.

Prospective associations between prenatal adversities and borderline personality disorder at 11-12 years

BACKGROUND

The aetiological pathways to borderline personality disorder (BPD) remain only partly elucidated. Retrospective research indicates that prenatal adversity may be an important early risk factor in the development of BPD. This requires corroboration with prospective longitudinal studies.

METHOD

A community sample of 6050 mothers and their children (born between April 1991 and December 1992) were assessed. Maternal anxiety and depression and maternal alcohol and tobacco consumption were assessed during pregnancy (18 and 32 weeks gestation). Postnatal risks, including maladaptive parenting (suboptimal parenting and parent conflict), family adversity, maternal anxiety and depression and maternal alcohol and tobacco consumption, were assessed during early childhood. Internalizing and externalizing symptoms were assessed in late childhood. Trained psychologists interviewed children in late childhood to ascertain the presence of BPD (at least five probable/definite symptoms).

RESULTS

In unadjusted analyses, all prenatal risk factors (i.e., maternal alcohol and tobacco consumption and maternal anxiety and depression) were significantly associated with BPD. Following adjustment for sex, birthweight and postnatal exposure to anxiety and depression respectively, maladaptive parenting, family adversity and child's internalizing and externalizing symptoms, prenatal anxiety at 18 weeks gestation [odds ratio (OR) 1.57, 95% confidence interval (CI) 1.18-2.09] and depression at 18 weeks (OR 1.59, 95% CI 1.08-2.32) and 32 weeks (OR 1.57, 95% CI 1.14-2.18) gestation remained significantly associated with BPD.

CONCLUSIONS

This study provides prospective evidence of associations between prenatal adversities and BPD at 11-12 years. Prenatal anxiety and depression were independently associated with BPD, suggesting that they may exert direct effects on BPD during the prenatal period. This highlights the importance of programmes to reduce maternal stress during pregnancy.

Prenatal tobacco exposure and infant stress reactivity: role of child sex and maternal behavior

This study examined the association between prenatal tobacco exposure (PTE) and infant cortisol reactivity at 9 months of infant age. Child sex and maternal parenting behavior were hypothesized moderators. The sample included 217 (148 tobacco-exposed, 69 non-exposed) mother-child dyads. Data used were obtained from pregnancy assessments, mother-infant feeding interactions at 2 months, and salivary cortisol at four time points in response to frustration at 9 months. Results indicated a significant association between PTE and infant cortisol that was moderated by infant sex and maternal intrusiveness. That is, PTE boys had lower cortisol than control boys, but there was no association between PTE and cortisol among girls. There was a significant association between PTE and cortisol among infants of intrusive mothers, but not among infants with non-intrusive mothers. Thus, PTE was associated with cortisol hypo-reactivity such that boys and non-exposed infants experiencing high maternal intrusiveness were at greater risk.

Determining the impact of prenatal tobacco exposure on self-regulation at 6 months

Our goal in the present study was to examine the effects of maternal smoking during pregnancy on infant self-regulation, exploring birth weight as a mediator and sex as a moderator of risk. A prospective sample of 218 infants was assessed at 6 months of age. Infants completed a battery of tasks assessing working memory/inhibition, attention, and emotional reactivity and regulation. Propensity scores were used to statistically control for confounding risk factors associated with maternal smoking during pregnancy. After prenatal and postnatal confounds were controlled, prenatal tobacco exposure was related to reactivity to frustration and control of attention during stimulus encoding. Birth weight did not mediate the effect of prenatal exposure but was independently related to reactivity and working memory/inhibition. The effect of tobacco exposure was not moderated by sex.

Prenatal tobacco exposure and brain morphology: a prospective study in young children

It is well known that smoking during pregnancy can affect offspring health. Prenatal tobacco exposure has been associated with negative behavioral and cognitive outcomes in childhood, adolescence, and young adulthood. These associations between prenatal tobacco exposure and psychopathology in offspring could possibly be explained by the influence of prenatal tobacco exposure on brain development. In this prospective study, we investigated the association between prenatal tobacco exposure, behavioral and emotional functioning and brain morphology in young children. On the basis of age and gender, we matched 113 children prenatally exposed to tobacco with 113 unexposed controls. These children were part of a population-based study in the Netherlands, the Generation R Study, and were followed from pregnancy onward. Behavioral and emotional functioning was assessed at age 6 with the Child Behavior Checklist. We assessed brain morphology using magnetic resonance imaging techniques in children aged 6-8 years. Children exposed to tobacco throughout pregnancy have smaller total brain volumes and smaller cortical gray matter volumes. Continued prenatal tobacco exposure was associated with cortical thinning, primarily in the superior frontal, superior parietal, and precentral cortices. These children also demonstrated increased scores of affective problems. In addition, thickness of the precentral and superior frontal cortices was associated with affective problems. Importantly, brain development in offspring of mothers who quit smoking during pregnancy resembled that of nonexposed controls (no smaller brain volumes and no thinning of the cortex). Our findings suggest an association between continued prenatal tobacco exposure and brain structure and function in school-aged children.

Do dopamine gene variants and prenatal smoking interactively predict youth externalizing behavior?

Externalizing behaviors (encompassing antisocial, impulsive, and substance use behaviors) are pervasive and impairing across a multitude of settings and developmental contexts. These behaviors, though often investigated separately, are highly comorbid. Prenatal tobacco exposure in interaction with various genetic influences has predicted later externalizing behavior, and recent evidence supports investigating sex differences in these patterns. In the current study, we extend this work by (a) examining two functional genetic markers in the dopamine system: the transporter gene (DAT1) and the dopamine receptor D4 gene (DRD4) in interaction with prenatal tobacco exposure to predict a latent composite of externalizing behavior and (b) testing whether these patterns differ by sex of youth in a community sample of adolescents (n=176). The relatively small sample is partially offset by high quality, multi-method prospective measurement. We assessed prenatal tobacco exposure using prospective repeated cotinine-corrected reports and externalizing behaviors were assessed utilizing multiple measures across three waves. The interaction between DAT1 (but not DRD4) and prenatal tobacco exposure was statistically significant in boys, and patterns appeared to differ by sex. Risk for externalizing behaviors for exposed boys increased linearly as a function of the 10r DAT1 allele. For exposed girls, there was a trend such that DAT1 heterozygotes had a marginally higher risk than homozygotes. This pattern was not explained by passive gene-environment correlation. Elucidating sex-specific pathways through which early adverse exposures and genetic susceptibilities contribute to externalizing behavior can inform early targeted prevention efforts for those children at highest risk.

A new look at quantifying tobacco exposure during pregnancy using fuzzy clustering

BACKGROUND

Prenatal tobacco exposure is a risk factor for the development of externalizing behaviors and is associated with several adverse health outcomes. Because pregnancy smoking is a complex behavior with both daily fluctuations and changes over the course of pregnancy, quantifying tobacco exposure is a significant challenge. To better measure the degree of tobacco exposure, costly biological specimens and repeated self-report measures of smoking typically are collected throughout pregnancy. With such designs, there are multiple, and substantially correlated, indices that can be integrated via new statistical methods to identify patterns of prenatal exposure.

METHOD

A multiple-imputation-based fuzzy clustering technique was designed to characterize topography of prenatal exposure. This method leveraged all repeatedly measured maternal smoking variables in our sample data, including (a) cigarette brand; (b) Fagerstrom nicotine dependence item scores; (c) self-reported smoking; and (d) cotinine level in maternal urine and infant meconium samples. Identified exposure groups then were confirmed using a suite of clustering validation indices based on multiple imputed datasets. The classifications were validated against irritable reactivity in the first month of life and birth weight of 361 neonates (Male(_n)=185; Female(_n)=176; Gestational Age_(Mean)=39weeks).

RESULTS

This proposed approach identified three exposure groups, non-exposed, lighter-tobacco-exposed, and heavier-tobacco-exposed based on high-dimensional attributes. Unlike cut-off score derived groups, these groupings reflect complex smoking behavior and individual variation of nicotine metabolism across pregnancy. The identified groups predicted differences in birth weight and in the pattern of change in neonatal irritable reactivity, as well as resulted in increased predictive power. Multiple-imputation-based fuzzy clustering appears to be a useful method to categorize patterns of exposure and their impact on outcomes.

Prenatal tobacco exposure: developmental outcomes in the neonatal period

Smoking during pregnancy is a persistent public health problem that has been linked to later adverse outcomes. The neonatal period--the first month of life--carries substantial developmental change in regulatory skills and is the period when tobacco metabolites are cleared physiologically. Studies to date mostly have used cross-sectional designs that limit characterizing potential impacts of prenatal tobacco exposure on the development of key self-regulatory processes and cannot disentangle short-term withdrawal effects from residual exposure-related impacts. In this study, pregnant participants (N = 304) were recruited prospectively during pregnancy, and smoking was measured at multiple time points, with both self-report and biochemical measures. Neonatal attention, irritable reactivity, and stress dysregulation were examined longitudinally at three time points during the first month of life, and physical growth indices were measured at birth. Tobacco-exposed infants showed significantly poorer attention skills after birth, and the magnitude of the difference between exposed and nonexposed groups attenuated across the neonatal period. In contrast, exposure-related differences in irritable reactivity largely were not evident across the 1st month of life, differing marginally at 4 weeks of age only. Third-trimester smoking was associated with pervasive, deleterious, dose–response impacts on physical growth measured at birth, whereas nearly all smoking indicators throughout pregnancy predicted level and growth rates of early attention. The observed neonatal pattern is consistent with the neurobiology of tobacco on the developing nervous system and fits with developmental vulnerabilities observed later in life.

Effects of prenatal tobacco exposure on gene expression profiling in umbilical cord tissue

Maternal smoking doubles the risk of delivering a low birth weight infant. The purpose of this study was to analyze differential gene expression in umbilical cord tissue as a function of maternal smoking, with an emphasis on growth-related genes. We recruited 15 pregnant smokers and 15 women who never smoked during pregnancy to participate. RNA was isolated from umbilical cord tissue collected and snap frozen at the time of delivery. Microarray analysis was performed using the Affymetrix GeneChip Scanner 3000. Six hundred seventy-eight probes corresponding to 545 genes were differentially expressed (i.e. had an intensity ratio > +/- 1.3 and a corrected significance value p < 0.005) in tissue obtained from smokers versus nonsmokers. Genes important for fetal growth, angiogenesis, or development of connective tissue matrix were upregulated among smokers. The most highly upregulated gene was CSH1, a somatomammotropin gene. Two other somatomammotropin genes (CSH2 and CSH-L1) were also upregulated. The most highly downregulated gene was APOBEC3A; other downregulated genes included those that may be important in immune and barrier protection. Validation of the three somatomammotropin genes showed a high correlation between qPCR and microarray expression. We conclude that maternal smoking may be associated with altered gene expression in the offspring.

Exposures to environmental toxicants and attention deficit hyperactivity disorder in U.S. children

OBJECTIVE

The purpose of this study was to examine the association of exposures to tobacco smoke and environmental lead with attention deficit hyperactivity disorder (ADHD).

METHODS

Data were obtained from the National Health and Nutrition Examination Survey 1999-2002. Prenatal and postnatal tobacco exposure was based on parent report; lead exposure was measured using blood lead concentration. ADHD was defined as having current stimulant medication use and parent report of ADHD diagnosed by a doctor or health professional.

RESULTS

Of 4,704 children 4-15 years of age, 4.2% were reported to have ADHD and stimulant medication use, equivalent to 1.8 million children in the United States. In multivariable analysis, prenatal tobacco exposure [odds ratio (OR) = 2.5; 95% confidence interval (CI), 1.2-5.2] and higher blood lead concentration (first vs. fifth quintile, OR = 4.1; 95% CI, 1.2-14.0) were significantly associated with ADHD. Postnatal tobacco smoke exposure was not associated with ADHD (OR = 0.6; 95% CI, 0.3-1.3; p = 0.22). If causally linked, these data suggest that prenatal tobacco exposure accounts for 270,000 excess cases of ADHD, and lead exposure accounts for 290,000 excess cases of ADHD in U.S. children.

CONCLUSIONS

We conclude that exposure to prenatal tobacco and environmental lead are risk factors for ADHD in U.S. children.