Associations of prenatal maternal smoking with offspring hyperactivity: causal or confounded?

Systematic Review and Meta-analysis of the Relationship Between Exposure to Parental Substance Use and Attention-Deficit/Hyperactivity Disorder in Children

Attention-deficit/hyperactivity disorder (ADHD) is characterized by persistent patterns of inattention, hyperactivity, and impulsiveness. Among US children and adolescents aged 3-17 years, 9.4% have a diagnosis of ADHD. Previous research suggests possible links between parental substance use and ADHD among children. We conducted a systematic review and meta-analysis of 86 longitudinal or retrospective studies of prenatal or postnatal alcohol, tobacco, or other parental substance use and substance use disorders and childhood ADHD and its related behavioral dimensions of inattention and hyperactivity-impulsivity. Meta-analyses were grouped by drug class and pre- and postnatal periods with combined sample sizes ranging from 789 to 135,732. Prenatal exposure to alcohol or tobacco and parent substance use disorders were consistently and significantly associated with ADHD among children. Other parental drug use exposures resulted in inconsistent or non-significant findings. Prevention and treatment of parental substance use may have potential for impacts on childhood ADHD.

Safety and efficacy of antioxidant therapy in children and adolescents with attention deficit hyperactivity disorder: A systematic review and network meta-analysis

OBJECTIVE

To systematically evaluate the safety and efficacy of antioxidant therapy in children and adolescents with attention deficit hyperactivity disorder (ADHD).

METHODS

Randomized controlled trials and prospective studies on antioxidant therapy in children and adolescents with ADHD were searched in PubMed, Embase, and Cochrane Library from the inception of databases to November 12, 2022. Two investigators independently screened the literature, extracted data, and evaluated the quality of the included studies. Network meta-analysis (PROSPERO registration number CRD 42023382824) was carried out by using R Studio 4.2.1.

RESULTS

48 studies involving 12 antioxidant drugs (resveratrol, pycnogenol, omega-3, omega-6, quercetin, phosphatidylserine, almond, vitamin D, zinc, folic acid, ginkgo biloba, Acetyl-L-carnitine) were finally included, with 3,650 patients. Network meta-analysis showed that omega-6 (0.18), vitamin D (0.19), and quercetin (0.24) were the top three safest drugs according to SUCRA. The omega-3 (SUCRA 0.35), pycnogenol (SUCRA 0.36), and vitamin D (SUCRA 0.27) were the most effective in improving attention, hyperactivity, and total score of Conners' parent rating scale (CPRS), respectively. In terms of improving attention, hyperactivity, and total score of Conners' teacher rating scale (CTRS), pycnogenol (SUCRA 0.32), phosphatidylserine+omega-3 (SUCRA 0.26), and zinc (SUCRA 0.34) were the most effective, respectively. In terms of improving attention, hyperactivity and total score of ADHD Rating Scale-Parent, the optimal agents were phosphatidylserine (SUCRA 0.39), resveratrol+MPH (SUCRA 0.24), and phosphatidylserine (SUCRA 0.34), respectively. In terms of improving attention, hyperactivity and total score of ADHD Rating Scale-Teacher, pycnogenol (SUCRA 0.32), vitamin D (SUCRA 0.31) and vitamin D (SUCRA 0.18) were the optimal agents, respectively. The response rate of omega-3+6 was the highest in CGI (SUCRA 0.95) and CPT (SUCRA 0.42).

CONCLUSION

The rankings of safety and efficacy of the 12 antioxidants vary. Due to the low methodological quality of the included studies, the probability ranking cannot fully explain the clinical efficacy, and the results need to be interpreted with caution. More high-quality studies are still needed to verify our findings.

Prenatal and Childhood Smoke Exposure Associations with Cognition, Language, and Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

To assess the relationships of prenatal and childhood smoke exposure with specific neurodevelopmental and behavioral problems during early childhood.

STUDY DESIGN

A subsample (n = 386) of mother-child dyads from the Newborn Epigenetic Study (NEST) prebirth cohort participated in the study. Cotinine concentrations were used to objectively measure prenatal and childhood smoke exposure when youth were aged 3-13 years. Multivariable regression models were used to estimate associations of prenatal and childhood cotinine concentrations with performance on the National Institutes of Health (NIH) Toolbox and attention-deficit/hyperactivity disorder and behavioral symptoms, measured using the Behavior Assessment System for Children, 2nd edition (BASC-2).

RESULTS

After adjusting for confounders, childhood cotinine concentrations were associated with poorer cognitive performance on tasks measuring cognitive flexibility (B = -1.29; P = .03), episodic memory (B = -0.97; P = .02), receptive language development (B = -0.58; P = .01), and inhibitory control and attention (B = -1.59; P = .006). Although childhood cotinine concentration was associated with higher levels of attention problems (B = 0.83; P = .004) on the BASC-2, after adjustment for confounders, the association is nonsignificant. Although associations for maternal cotinine concentrations were null, an interaction was detected between prenatal and childhood cotinine concentrations on the NIH Toolbox Picture Vocabulary Task (P = .02).

CONCLUSIONS

Our findings suggest that childhood tobacco smoke exposure may lead to poorer attention regulation and language acquisition, complex visual processing ability, and attention problems.

Distinct sex-dependent effects of maternal preconception nicotine and enrichment on the early development of rat offspring brain and behavior

Developmental nicotine exposure is harmful to offspring. Whereas much is known about the consequences of prenatal nicotine exposure, relatively little is understood about how maternal preconception nicotine impacts the next generation. Positive experiences, such as environmental enrichment/complexity, have considerable potential to improve developmental outcomes and even treat and prevent drug addiction. Therefore, the current study sought to identify how maternal exposure to moderate levels of nicotine prior to conception impacts offspring development, and if the presumably negative consequence of nicotine could be reversed by concurrent exposure to an enriched environment. We treated female Long Evans rats with nicotine in their drinking water (15 mg nicotine salt/L) for seven weeks while residing in either standard or enriched conditions. Both experiences occurred exclusively prior to mating. Nicotine exposure reduced dam fertility by ~20% (p = .06). Females reared their own litters, and offspring were tested in two assessments of early development: negative geotaxis and open field. Offspring were euthanized at weaning (P21), and their brains were processed with Golgi-Cox solution to allow quantification of dendritic spine density. Results indicate that neither maternal nicotine or enrichment had an impact on maternal care, but male offspring were impaired at negative geotaxis due to maternal nicotine, female offspring showed altered open field exploration due to maternal enrichment, and offspring of both sexes had increased spine density in OFC due to maternal enrichment. Therefore, this experiment provides novel insights into the unique, sex-dependent consequences of maternal preconception nicotine and enrichment on the early development of rat behavior and brain.

Invited Commentary: Sibling-Comparison Designs, Are They Worth the Effort?

In this issue of the Journal, von Ehrenstein et al. (Am J Epidemiol. 2021;190(5):728-737) add to the large and growing literature on the potentially causal association between prenatal exposure to maternal smoking and neuropsychiatric health. In addition to statewide, prospectively collected data, a particular strength was their ability to perform a sibling-comparison design, contrasting the rate of autism spectrum disorder in siblings discordantly exposed to maternal smoking. Unfortunately, the estimate from the sibling pairs could neither confirm nor refute the conclusions based on the full cohort. Interpretation was hampered by broad confidence limits, and even had power been higher, the authors acknowledge a range of potential biases that would have made it difficult to draw any firm conclusions from a similarity or difference in the sibling-pair estimate and estimate from the full cohort. Was the addition of the sibling comparison actually worth the effort? In this commentary, I will briefly summarize the benefits and limitations of this design, and, with some caveats, argue that its inclusion in the study by von Ehrenstein et al. was indeed a strength and not just an ornamentation.

Family-Based Designs that Disentangle Inherited Factors from Pre- and Postnatal Environmental Exposures: In Vitro Fertilization, Discordant Sibling Pairs, Maternal versus Paternal Comparisons, and Adoption Designs

Identifying environmental risk and protective exposures that have causal effects on health is an important scientific goal. Many environmental exposures are nonrandomly allocated and influenced by dispositional factors including inherited ones. We review family-based designs that can separate the influence of environmental exposures from inherited influences shared between parent and offspring. We focus on prenatal exposures. We highlight that the family-based designs that can separate the prenatal environment from inherited confounds are different to those that are able to pull apart later-life environmental exposures from inherited confounds. We provide a brief review of the literature on maternal smoking during pregnancy and offspring attention-deficit/hyperactivity disorder (ADHD) and conduct problems; these inconsistencies in the literature make a review useful and this illustrates that results of family-based genetically informed studies are inconsistent with a causal interpretation for this exposure and these two offspring outcomes.

Association between environmental tobacco smoke exposure across the first four years of life and manifestation of externalizing behavior problems in school-aged children

BACKGROUND

Extensive literature in human and animal models has documented an association between maternal smoking during pregnancy and externalizing behavior in offspring. It remains unclear; however, the extent to which postnatal environmental smoke exposure is associated with behavioral development, particularly for children whose mothers did not smoke during pregnancy. The present study examined whether magnitude of exposure to environmental smoke across the first four years of life demonstrated a linear association with later externalizing symptoms.

METHODS

Exposure was quantified through salivary cotinine measured when children were 6, 15, 24, and 48 months of age, providing a more accurate quantification of realized exposure than can be estimated from parental report of cigarettes smoked. Data were available for n = 1,096 (50% male; 44% African American) children recruited for the Family Life Project, a study of child development in areas of rural poverty.

RESULTS

Analyses indicate a linear association between cotinine and children's symptoms of hyperactivity and conduct problems. This association remained significant after controlling for family poverty level, parental education, parental history of ADHD, hostility, depression, caregiver IQ, and obstetric complications. Furthermore, this association was unchanged when excluding mothers who smoked during pregnancy from the model.

CONCLUSIONS

Findings are consistent with animal models demonstrating an effect of environmental exposure to nicotine on ongoing brain development in regions related to hyperactivity and impulsivity, and highlight the importance of mitigating children's exposure to environmental smoke, including sources that extend beyond the parents.

Prenatal alcohol exposure and developmental programming of mental illness

It is well established that high-dose alcohol consumption during pregnancy increases the risk for a plethora of adverse offspring outcomes. These include neurodevelopmental, cognitive and social deficits, as well as psychiatric illnesses, such as depression and anxiety. However, much less evidence is available on the effects of low- and early-dose alcohol exposure on mental health outcomes, regardless of the accumulating evidence that mental health outcomes should be considered in the context of the Developmental Origins of Health and Disease hypothesis. This review will discuss the evidence that indicates low-dose and early prenatal alcohol exposure can increase the risk of mental illness in offspring and discuss the mechanistic pathways that may be involved.

Examining the Association Between Maternal Smoking During Pregnancy and Child Behavior Problems Using Quality-Adjusted Life Years

Objectives Examining the association between maternal smoking and losses in childhood health-related quality of life due to behavior problems provides parents and policymakers another tool for the valuation of smoking cessation during pregnancy. Methods Using the National Longitudinal Survey of Youth 1979 Child and Young Adult data, this study retrospectively examined a cohort of 4114 women and 8668 children. In addition to questions focusing on maternal smoking and general demographics, each survey included the Behavior Problems Index (BPI), a 28-item questionnaire with six subscales measuring childhood behavior problems (antisocial behavior, anxiousness/depression, headstrongness, hyperactivity, immature dependency, and peer conflict/social withdrawal). Responses to the BPI, completed by mothers with children ages 4-14, were summarized on a QALY scale using published preference weights. Results Children whose mothers smoked during pregnancy experience additional QALY losses of 0.181, on average, per year due to increased behavior problems. Boys suffered larger QALY losses associated with maternal smoking (0.242) compared to girls (0.119; p value = .021), regardless of age. Moreover, heavier smoking during pregnancy (i.e., 1 or more packs/day) was associated with larger QALY losses (0.282; p-value < .001). Conclusions for Practice These findings illustrate the burden of maternal smoking during pregnancy on child health, namely behavioral problems. The losses in QALYs may be incorporated into economic evaluations for smoking cessation interventions during pregnancy. Future research will investigate how maternal smoking following childbirth is associated with child QALYs.

Negative control exposure studies in the presence of measurement error: implications for attempted effect estimate calibration

Background

Negative control exposure studies are increasingly being used in epidemiological studies to strengthen causal inference regarding an exposure-outcome association when unobserved confounding is thought to be present. Negative control exposure studies contrast the magnitude of association of the negative control, which has no causal effect on the outcome but is associated with the unmeasured confounders in the same way as the exposure, with the magnitude of the association of the exposure with the outcome. A markedly larger effect of the exposure on the outcome than the negative control on the outcome strengthens inference that the exposure has a causal effect on the outcome.

Methods

We investigate the effect of measurement error in the exposure and negative control variables on the results obtained from a negative control exposure study. We do this in models with continuous and binary exposure and negative control variables using analysis of the bias of the estimated coefficients and Monte Carlo simulations.

Results

Our results show that measurement error in either the exposure or negative control variables can bias the estimated results from the negative control exposure study.

Conclusions

Measurement error is common in the variables used in epidemiological studies; these results show that negative control exposure studies cannot be used to precisely determine the size of the effect of the exposure variable, or adequately adjust for unobserved confounding; however, they can be used as part of a body of evidence to aid inference as to whether a causal effect of the exposure on the outcome is present.

Aggressive behaviour in childhood and adolescence: the role of smoking during pregnancy, evidence from four twin cohorts in the EU-ACTION consortium

BACKGROUND

Maternal smoking during pregnancy (MSDP) has been linked to offspring's externalizing problems. It has been argued that socio-demographic factors (e.g. maternal age and education), co-occurring environmental risk factors, or pleiotropic genetic effects may account for the association between MSDP and later outcomes. This study provides a comprehensive investigation of the association between MSDP and a single harmonized component of externalizing: aggressive behaviour, measured throughout childhood and adolescence.

METHODS

Data came from four prospective twin cohorts - Twins Early Development Study, Netherlands Twin Register, Childhood and Adolescent Twin Study of Sweden, and FinnTwin12 study - who collaborate in the EU-ACTION consortium. Data from 30 708 unrelated individuals were analysed. Based on item level data, a harmonized measure of aggression was created at ages 9-10; 12; 14-15 and 16-18.

RESULTS

MSDP predicted aggression in childhood and adolescence. A meta-analysis across the four samples found the independent effect of MSDP to be 0.4% (r = 0.066), this remained consistent when analyses were performed separately by sex. All other perinatal factors combined explained 1.1% of the variance in aggression across all ages and samples (r = 0.112). Paternal smoking and aggressive parenting strategies did not account for the MSDP-aggression association, consistent with the hypothesis of a small direct link between MSDP and aggression.

CONCLUSIONS

Perinatal factors, including MSDP, account for a small portion of the variance in aggression in childhood and adolescence. Later experiences may play a greater role in shaping adolescents' aggressive behaviour.

Identifying the contribution of prenatal risk factors to offspring development and psychopathology: What designs to use and a critique of literature on maternal smoking and stress in pregnancy

Identifying prenatal environmental factors that have genuinely causal effects on psychopathology is an important research priority, but it is crucial to select an appropriate research design. In this review we explain why and what sorts of designs are preferable and focus on genetically informed/sensitive designs. In the field of developmental psychopathology, causal inferences about prenatal risks have not always been based on evidence generated from appropriate designs. We focus on reported links between maternal smoking during pregnancy and offspring attention-deficit/hyperactivity disorder or conduct problems. Undertaking a systematic review of findings from genetically informed designs and “triangulating” evidence from studies with different patterns of bias, we conclude that at present findings suggest it is unlikely that there is a substantial causal effect of maternal smoking in pregnancy on either attention-deficit/hyperactivity disorder or conduct problems. In contrast, for offspring birth weight (which serves as a positive control) findings strongly support a negative causal effect of maternal smoking in pregnancy. For maternal pregnancy stress, too few studies use genetically sensitive designs to draw firm conclusions, but continuity with postnatal stress seems important. We highlight the importance of moving beyond observational designs, for systematic evaluation of the breadth of available evidence and choosing innovative designs. We conclude that a broader set of prenatal risk factors should be examined, including those relevant in low- and middle-income contexts. Future directions include a greater use of molecular genetically informed designs such as Mendelian randomization to test causal hypotheses about prenatal exposure and offspring outcome.

Prenatal exposure to maternal smoking during pregnancy and attention-deficit/hyperactivity disorder in offspring: A meta-analysis

Some large population-based cohort studies highlighted the risk of maternal smoking during pregnancy (MSDP) for children attention-deficit/hyperactivity disorder (ADHD). However, the causality of this association is still controversial. Here we performed a meta-analysis trying to clarify the association between prenatal exposure to MSDP and ADHD in offspring. After publication screening, 27 eligible original articles with a total of 3076173 subjects were included. The results showed that either prenatal exposure to MSDP or smoking cessation during first trimester was significantly associated with childhood ADHD after adjusting for parental psychiatric history and social socioeconomic status. Smoking cessation before pregnancy, which was not significantly associated with childhood ADHD, was strongly recommended for female smokers planning to conceive. Inconsistent results were obtained in the meta-analysis on the risk of maternal passive smoking during pregnancy caused by paternal smoking. We also found that risk of MSDP for childhood ADHD varied across geographic regions.

Maternal Smoking and Attention-Deficit/Hyperactivity Disorder in Offspring: A Meta-analysis

CONTEXT

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in childhood. Exploring the risk factors for ADHD is helpful in preventing ADHD.

OBJECTIVE

To explore the association between maternal smoking during pregnancy and the occurrence of ADHD in offspring.

DATA SOURCES

PubMed, Embase, and Cochrane Library were searched from inception to May 2017 for studies.

STUDY SELECTION

Cohort or case-control studies in which the association between maternal smoking and ADHD in offspring were investigated were eligible if they included odds ratios (ORs), hazard ratios, or risk ratios and 95% confidence intervals (CIs).

DATA EXTRACTION

Two investigators independently extracted data on definition of exposure and outcome, number of cases and total sample population, and potential confounders adjusted. Any dose-relationship data for smoking and ADHD risk were also extracted.

RESULTS

Fifteen cohort studies and 5 case-control studies with 50 044 cases and 2 998 059 participants were included. Smoking during pregnancy increased the risk of offspring ADHD (OR: 1.60; 95% CI: 1.45-1.76). The risk of ADHD was greater for children whose mothers were heavy smokers (OR: 1.75; 95% CI: 1.51-2.02) than for those mothers were light smokers (OR: 1.54; 95% CI: 1.40-1.70).

LIMITATIONS

The limitations of our study included different assessment tools of ADHD and a lack of objective biological measures for maternal smoking.

CONCLUSIONS

With our meta-analysis, we provide evidence for an association between maternal smoking and offspring ADHD but do not solve the causality issues concerning potential confounding by other risk factors. More high-quality studies are needed to establish whether the association with smoking is causal.

Prenatal Exposure to Environmental Tobacco Smoke and Hyperactivity Behavior in Chinese Young Children

This study aimed to examine the association between prenatal environmental tobacco smoke (ETS) exposure and hyperactivity behaviors in young children. A cross-sectional study was undertaken among 21,243 participants from all of the kindergartens in Longhua District of Shenzhen, China. Multivariate logistic regression models and hierarchical linear models were employed to assess the associations. After adjusting for potential confounders of gender, preterm birth, birth asphyxiation, etc., prenatal ETS exposure was significantly associated with an increased risk of hyperactivity behaviors in young children (OR (95% CI) = 1.51 (1.28-1.77); β (95% CI) = 0.017 (0.013-0.020)). Along with increases in children's prenatal ETS exposure dose (measured by daily ETS exposure duration, daily cigarette consumption by household members, and overall score of prenatal ETS exposure), the children were also increasingly more likely to exhibit hyperactivity behaviors. Furthermore, children whose mothers had prenatal ETS exposure in any one or more of the pregnancy trimesters were more likely to exhibit hyperactivity behaviors as compared with those born to non-exposure mothers (all p < 0.05). Overall, prenatal ETS exposure could be associated with a detrimental impact on offspring's hyperactivity behaviors, and public health efforts are needed to reduce prenatal ETS exposure.

Neurodevelopmental Disorders and Environmental Toxicants: Epigenetics as an Underlying Mechanism

The increasing prevalence of neurodevelopmental disorders, especially autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD), calls for more research into the identification of etiologic and risk factors. The Developmental Origin of Health and Disease (DOHaD) hypothesizes that the environment during fetal and childhood development affects the risk for many chronic diseases in later stages of life, including neurodevelopmental disorders. Epigenetics, a term describing mechanisms that cause changes in the chromosome state without affecting DNA sequences, is suggested to be the underlying mechanism, according to the DOHaD hypothesis. Moreover, many neurodevelopmental disorders are also related to epigenetic abnormalities. Experimental and epidemiological studies suggest that exposure to prenatal environmental toxicants is associated with neurodevelopmental disorders. In addition, there is also evidence that environmental toxicants can result in epigenetic alterations, notably DNA methylation. In this review, we first focus on the relationship between neurodevelopmental disorders and environmental toxicants, in particular maternal smoking, plastic-derived chemicals (bisphenol A and phthalates), persistent organic pollutants, and heavy metals. We then review studies showing the epigenetic effects of those environmental factors in humans that may affect normal neurodevelopment.

Perinatal smoking exposure and behavioral problems in Japanese children aged 5 years: The Kyushu Okinawa Maternal and Child Health Study

BACKGROUND

Epidemiological evidence regarding the relationship between maternal secondhand smoke (SHS) exposure during pregnancy and postnatal SHS exposure and childhood behavioral problems is scarce.

OBJECTIVE

The present prebirth cohort study investigated the association between perinatal smoking exposure and behavioral problems in Japanese children aged 5 years.

METHODS

Subjects were 1200 mother-child pairs. Data on variables under study were obtained using parent questionnaires. Emotional problems, conduct problems, hyperactivity problems, and peer problems were assessed using the Strengths and Difficulties Questionnaire. Adjustment was made for maternal age, gestation at baseline, region of residence at baseline, number of children at baseline, maternal and paternal education, household income, maternal depressive symptoms during pregnancy, maternal alcohol intake during pregnancy, child's birth weight, child's sex, and breastfeeding duration.

RESULTS

Maternal smoking during pregnancy was independently associated with increased risk of conduct problems and hyperactivity problems (adjusted odds ratios: ORs [95% confidence intervals: CIs]=1.93 [1.15-3.17] and 1.89 [1.03-3.33], respectively). Maternal SHS exposure at work during pregnancy was independently positively related to conduct problems and hyperactivity problems (adjusted ORs [95% CI]=1.54 [1.01-2.31] and 1.69 [1.04-2.67], respectively). Smoking by any household member, and especially by the child's father, during the first year of life was independently associated with an increased risk of emotional problems (adjusted ORs [95% CI]=1.55 [1.06-2.26] and 1.63 [1.11-2.40], respectively).

CONCLUSIONS

Maternal smoking and maternal SHS exposure at work during pregnancy may increase the risk of conduct problems and hyperactivity problems. Smoking by any household member, and especially by the child's father, may increase the risk of emotional problems.

Just DO(HaD) It! Testing the clinical potential of the DOHaD hypothesis to prevent mental disorders using experimental study designs

Optimal early cognitive and emotional development are vital to reaching one's full potential and represent our best chance to improve the mental health of the population. The developmental origins of health and disease (DOHaD) hypothesis posits that adverse perinatal exposures can alter physiology and increase disease risk. As physiological plasticity decreases with age, interventions applied during gestation may hold the most promise for reducing the impact of mental disorders across the lifespan. However, this vast clinical potential remains largely unrealized as the majority of human DOHaD research is observational in nature. The application of more rigorous experimental designs [e.g. Randomized Controlled Trials (RCTs)] not only represents a major step toward unlocking this potential, but are required to fully test the scientific validity of the DOHaD hypothesis as it pertains to mental illness. Here, we argue that the optimization of maternal diet and exercise during pregnancy represents our best chance to improve offspring neurodevelopment and reduce the burden of mental disorders. Follow-up studies of the offspring of pregnant women enrolled in new and existing RCTs of maternal gestational nutrition+exercise interventions are required to determine if acting during pregnancy can prevent and/or meaningfully reduce the prevalence and severity of mental disorders in the population.

Testing Causal Effects of Maternal Smoking During Pregnancy on Offspring's Externalizing and Internalizing Behavior

Maternal smoking during pregnancy (SDP) is associated with increased risk of externalizing and internalizing behaviors in offspring. Two explanations (not mutually exclusive) for this association are direct causal effects of maternal SDP and the effects of genetic and environmental factors common to parents and offspring which increase smoking as well as problem behaviors. Here, we examined the associations between parental SDP and mother rated offspring externalizing and internalizing behaviors (rated by the Child Behavior Checklist/2-3) at age three in a population-based sample of Dutch twins (N = 15,228 pairs). First, as a greater effect of maternal than of paternal SDP is consistent with a causal effect of maternal SDP, we compared the effects of maternal and paternal SDP. Second, as a beneficial effect of quitting smoking before pregnancy is consistent with the causal effect, we compared the effects of SDP in mothers who quit smoking before pregnancy, and mothers who continued to smoke during pregnancy. All mothers were established smokers before their pregnancy. The results indicated a greater effect of maternal SDP, compared to paternal SDP, for externalizing, aggression, overactive and withdrawn behavior. Quitting smoking was associated with less externalizing, overactive behavior, aggression, and oppositional behavior, but had no effect on internalizing, anxious depression, or withdrawn behavior. We conclude that these results are consistent with a causal, but small, effect of smoking on externalizing problems at age 3. The results do not support a causal effect of maternal SDP on internalizing behaviors.

Prenatal tobacco exposure and self-regulation in early childhood: Implications for developmental psychopathology

Prenatal tobacco exposure (PTE) has a well-documented association with disruptive behavior in childhood, but the neurocognitive effects of exposure that underlie this link are not sufficiently understood. The present study was designed to address this gap, through longitudinal follow-up in early childhood of a prospectively enrolled cohort with well-characterized prenatal exposure. Three-year-old children (n = 151) were assessed using a developmentally sensitive battery capturing both cognitive and motivational aspects of self-regulation. PTE was related to motivational self-regulation, where children had to delay approach to attractive rewards, but not cognitive self-regulation, where children had to hold information in mind and inhibit prepotent motor responses. Furthermore, PTE predicted motivational self-regulation more strongly in boys than in girls, and when propensity scores were covaried to control for confounding risk factors, the effect of PTE on motivational self-regulation was significant only in boys. These findings suggest that PTE's impact on neurodevelopment may be greater in boys than in girls, perhaps reflecting vulnerability in neural circuits that subserve reward sensitivity and emotion regulation, and may also help to explain why PTE is more consistently related to disruptive behavior disorders than attention problems.

Tobacco and alcohol use in pregnancy in France: the role of migrant status: the nationally representative ELFE study

INTRODUCTION

Tobacco and alcohol use in pregnancy are modifiable yet frequent risk factors of poor perinatal outcomes. We examined whether characteristics associated with substance use in pregnancy vary between native and migrant women, who often differ in terms of socio-demographic characteristics.

METHODS

Data come from a nationally representative sample of children born in France in 2011 (ELFE study, n=18,014). Maternal substance use in pregnancy (tobacco: ≥1 cigarette/day, alcohol: ≥1 time, binge drinking: ≥3 units of alcohol on one occasion) was assessed using survey methodology by a) trained interviewers and b) self-reports. Migration status was determined based on country of birth (native-born vs. migrant). The sample included 2330 migrant women, predominantly from North Africa (35.4% - primarily Algeria and Morocco), Sub-Saharan Africa (27.3% - primarily Senegal, Ivory Coast, the Congo and Cameroun), Europe (20.2% - primarily Portugal and Germany) and Asia (10.2% - primarily Turkey). Characteristics potentially associated with substance use included socio-demographics (maternal age, number of children, relationship status, educational attainment, employment status), health (psychological difficulties, incomplete prenatal care) and partner's characteristics (migration status, employment).

RESULTS

Compared to the native-born, migrant women had lower levels of tobacco smoking (8.8 vs. 21.9%) and alcohol use (23.4 vs. 40.7%), but not binge drinking (2.9 vs. 3.3%). Unfavorable socioeconomic circumstances were associated with tobacco smoking in native-born women only. Single parenthood was associated with alcohol use only in migrant women. In migrant women, co-occurring use of another substance and psychological difficulties were more strongly associated with use of tobacco, alcohol or binge drinking than in native-born women.

CONCLUSIONS

Migrant women have less favorable socioeconomic characteristics than native women but are generally less likely to use tobacco and alcohol in pregnancy. However those who experience single-parenthood need special attention, as they are disproportionately likely to use psychoactive substances which put them and their children at risk of poor health outcomes.

Maternal smoking and offspring inattention and hyperactivity: results from a cross-national European survey

In utero exposure to tobacco smoke is associated with adverse neonatal outcomes; the association with later childhood mental health outcomes remains controversial. We used a strategy involving comparison of maternal and paternal smoking reports in a sample pooling data from six diverse European countries. Data were drawn from mother (N = 4,517) and teacher (N = 4,611) reported attention deficit and hyperactivity disorder (ADHD) symptoms in school children aged 6-11 in Turkey, Romania, Bulgaria, Lithuania, Germany, and the Netherlands, surveyed in 2010. Mothers report on self and husband's smoking patterns during the pregnancy period. Logistic regression used with control covariates including demographics, maternal distress, live births, region, and post-pregnancy smoking. In unadjusted models, maternal prenatal smoking was associated with probable ADHD based on mother [Odds Ratio (OR) = 1.82, 95 % Confidence Interval (CI) 1.45-2.29], teacher (OR = 1.69, 95 % CI 1.33-2.14) and mother plus teacher (OR = 1.49, 95 % CI 1.03-2.17) report. Paternal prenatal smoking was similarly associated with probable ADHD in unadjusted models. When controlled for relevant confounders, maternal prenatal smoking remained a risk factor for offspring probable ADHD based on mother report (OR = 1.44, 95 % CI 1.06-1.96), whereas the effect of paternal prenatal smoking diminished (e.g., mother report: OR = 1.17, 95 % CI 0.92-1.49). Drawing on data from a diverse set of countries across Europe, we document that the association between maternal smoking and offspring ADHD is stronger than that of paternal smoking during the pregnancy period and offspring ADHD. To the extent that confounding is shared between parents, these results reflect a potential intrauterine influence of smoking on ADHD in children.

Maternal tobacco smoking in pregnancy and children's socio-emotional development at age 5: The EDEN mother-child birth cohort study

BACKGROUND

There is debate as to whether maternal tobacco use in pregnancy is related to offspring behaviour later on. We tested this association examining multiple aspects of children's behaviour at age 5 and accounting for parental smoking outside of pregnancy, as well as child and family characteristics.

METHODS

Data come from a prospective community based birth cohort study (EDEN; n=1113 families in France followed since pregnancy in 2003-2005 until the child's 5th birthday). Maternal tobacco use in pregnancy was self-reported. Children's socio-emotional development (emotional symptoms, conduct problems, symptoms of hyperactivity/inattention, peer relationship problems, prosocial behaviour) was assessed by mothers using the Strengths and Difficulties Questionnaire (SDQ) at age 5 years. Logistic regression analyses controlled for Inverse Probability Weights (IPW) of maternal tobacco use calculated based on study center, children's characteristics (sex, premature birth, low birth weight, breastfeeding), maternal characteristics (age at the child's birth, psychological difficulties and alcohol use in pregnancy, post-pregnancy depression, and smoking), paternal smoking in and post-pregnancy, parental educational attainment, family income, parental separation, and maternal negative life events.

RESULTS

Maternal smoking in pregnancy only predicted children's high symptoms of hyperactivity/inattention (sex and study center-adjusted ORs: maternal smoking in the 1st trimester: 1.95, 95%CI: 1.13-3.38; maternal smoking throughout pregnancy: OR=2.11, 95%CI: 1.36-3.27). In IPW-controlled regression models, only children of mothers who smoked throughout pregnancy had significantly elevated levels of hyperactivity/inattention (OR=2.20, 95%CI: 1.21-4.00).

CONCLUSIONS

Maternal tobacco smoking in pregnancy may contribute directly or through epigenetic mechanisms to children's symptoms of hyperactivity/inattention.

Psychopathologie et addiction des parents, situation sociale, et comportement de l’enfant

La consommation de tabac et d’alcool au cours de la grossesse peut augmenter les risques de santé pour l’enfant à court et plus long terme (petit poids de naissance, prématurité, difficultés cognitives et psychologiques) [1–5]. Les facteurs associés, qui incluent les difficultés sociales et économiques des familles (chômage, faibles revenus, absence du conjoint) [6], les difficultés psychologiques [1,7] et les consommations de tabac et d’alcool de l’entourage [1,8], sont mal connus chez les femmes migrantes. Nous avons examiné les facteurs associés aux consommations de tabac (≥ 1 cigarette/jour) et d’alcool (≥ 1 fois; binge drinking) des femmes de la cohorte ELFE en fonction de leur statut migratoire à partir de données recueillies à la maternité en 2011 (n = 18,316).

Les femmes nées en France consommaient plus que celles nées à l’étranger (tabac : 21,9 vs. 8,8 %; alcool : 40,4 vs. 22,9 %) mais les niveaux de binge drinking étaient comparables (3,2 vs. 2,9 %). Les consommations de tabac et d’alcool étaient associées aux caractéristiques démographiques, socio-économiques, de santé, et du père de l’enfant, avec des spécificités en fonction du statut migratoire : chez les femmes nées à l’étranger les consommations d’alcool sont associées aux fait de ne pas vivre avec un conjoint (OR ajusté : toute consommation : 2,20; binge drinking : 3,06); par contre une situation socioéconomique défavorable est associée à un niveau élevé de tabagisme et de binge drinking seulement chez les femmes nées en France. Les niveaux de consommations de tabac et alcool sont faibles lorsque le père de l’enfant est migrant, surtout chez les migrantes.

Au total, pour tenter de diminuer les niveaux de consommation de tabac et d’alcool au cours de la grossesse, les professionnels de santé et de prévention devraient tenir compte de multiples facteurs dont certains varient selon le statut migratoire des femmes.

Prenatal nicotine exposure and child behavioural problems

In utero exposure to tobacco smoke has been related to numerous adverse health effects in new-borns, infants, children, adolescents and adults. The aim of this review was to summarise findings on prenatal nicotine exposure and its relationship with behavioural problems in the offspring. The majority of studies, and especially several recent epidemiological studies, observed a higher likelihood for attention-deficit/hyperactivity disorder (ADHD) or ADHD symptoms in exposed subjects. However, both human and animal studies have failed to provide clear evidence on causality. Existing literature on studies investigating the association between prenatal nicotine exposure and conduct or externalising problems in the offspring suggests a causal effect. The establishment of a final conclusion concerning the relationship between prenatal nicotine exposure and internalising problems in the offspring is complicated by insufficient data and mixed results in epidemiological studies. Prenatal nicotine exposure has been associated with altered brain structure and function in human offspring, and a proposed biological mechanism is related to nicotine's adverse influence on neurotransmitter systems during brain development. In conclusion, establishing a statement on the causality of the relationship between prenatal nicotine exposure and behavioural problems in children remains a challenging task. Nevertheless, considering the results of an increasing number of studies which link prenatal exposure to nicotine to externalising problems applying different methodologies to account for confounding and in view of other adverse health effects known to be caused by this exposure, parents should consider smoking cessation.