Smoking in pregnancy and children's mental and motor development at age 1 and 5 years

DNA methylation at birth and fine motor ability in childhood: an epigenome-wide association study with replication

Lower fine motor performance in childhood has been associated with poorer cognitive development and neurodevelopmental conditions such as autism spectrum disorder, yet, biological underpinnings remain unclear. DNA methylation (DNAm), an essential process for healthy neurodevelopment, is a key molecular system of interest. In this study, we conducted the first epigenome-wide association study of neonatal DNAm with childhood fine motor ability and further examined the replicability of epigenetic markers in an independent cohort. The discovery study was embedded in Generation R, a large population-based prospective cohort, including a subsample of 924 ~ 1026 European-ancestry singletons with available data on DNAm in cord blood and fine motor ability at a mean (SD) age of 9.8 (0.4) years. Fine motor ability was measured using a finger-tapping test (3 subtests including left-, right-hand and bimanual), one of the most frequently used neuropsychological instruments of fine motor function. The replication study comprised 326 children with a mean (SD) age of 6.8 (0.4) years from an independent cohort, the INfancia Medio Ambiente (INMA) study. Four CpG sites at birth were prospectively associated with childhood fine motor ability after genome-wide correction. Of these, one CpG (cg07783800 in GNG4) was replicated in INMA, showing that lower levels of methylation at this site were associated with lower fine motor performance in both cohorts. GNG4 is highly expressed in the brain and has been implicated in cognitive decline. Our findings support a prospective, reproducible association between DNAm at birth and fine motor ability in childhood, pointing to GNG4 methylation at birth as a potential biomarker of fine motor ability.

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.

Switching from tobacco cigarettes in very early pregnancy: The effects of in utero e-cigarette exposure on mouse offspring neurodevelopment and behaviour

INTRODUCTION

Electronic cigarettes (e-cigarettes) are often perceived to be safer than smoking, which has led to some women switching to e-cigarettes during pregnancy. However, the effects of switching from smoking to e-cigarettes on both pregnancy outcomes and the foetus are largely unknown. This study aimed to investigate the effects of switching from tobacco smoking to e-cigarette use in very early pregnancy on birth outcomes, neurodevelopment and behaviour of the offspring.

METHODS

Female BALB/c mice were exposed to cigarette smoke for up to two weeks before being mated. Mated dams were then allocated to one of four treatment groups: (i) continued exposure to cigarette smoke (ii) exposure to e-cigarette aerosol with nicotine, (iii) or without nicotine, or (iv) medical air. Pregnant mice were exposed for 2 h per day for the duration of pregnancy. Gestational outcomes including litter size and sex ratio were assessed, in addition to early-life markers of physical- and neuro- development. At 8 weeks of age, motor coordination, anxiety, locomotion, memory and learning of the adult offspring were assessed.

RESULTS

Gestational outcomes and early markers of physical- and neuro- development were unaffected by in utero exposure, as well as locomotion, anxiety-like behaviour, and object recognition memory during adulthood. However, both e-cigarette groups displayed increased spatial recognition memory compared to air exposed controls. Maternal exposure to nicotine containing e-cigarette aerosol was found to increase offspring bodyweight and impair motor skill learning.

CONCLUSIONS

These results suggest there may be some benefits as well as negative effects of switching to e-cigarettes in early pregnancy.

Early factors associated with risk of developmental coordination disorder in very preterm children: A prospective area-based cohort study in Italy

BACKGROUND

Developmental coordination disorder (DCD) is a motor disorder of unknown aetiology that may have long-term consequences on daily activities, and psychological and physical health. Studies investigating risk factors for DCD have so far provided inconsistent results.

OBJECTIVES

To assess, using a parent-report screening tool, risk of DCD in school-age very preterm children born in Italy, and investigate the associated early biomedical and sociodemographic factors.

METHODS

A prospective area-based cohort (804 children, response rate 73.4%) was assessed at 8-11 years of age in three Italian regions. Perinatal data were abstracted from medical records. DCD risk was measured using the Italian-validated version of the Developmental Coordination Disorder Questionnaire (DCDQ-IT). For this study, children with cognitive deficit (i.e. intelligence quotient <70), cerebral palsy, severe vision and hearing disabilities, and other impairments affecting movement were excluded. A total of 629 children were analysed. We used inverse probability weighting to account for loss to follow-up, and multilevel, multivariable modified Poisson models to obtain adjusted risk ratio (aRR) and 95% confidence interval (CI). Missing values in the covariates were imputed.

RESULTS

195 children (weighted proportion 31.8%, 95% CI 28.2, 35.6) scored positive on the DCDQ-IT, corresponding to the 15th centile of the reference Movement-ABC test. Factors associated with overall DCD risk were male sex (aRR 1.35, 95% CI 1.05, 1.73), intrauterine growth restriction (aRR 1.45, 95% CI 1.14, 1.85), retinopathy of prematurity (aRR 1.62, 95% CI 1.07, 2.45), and older maternal age at delivery (aRR 1.39, 95% CI 1.09, 1.77). Complete maternal milk feeding at discharge from the neonatal unit and higher parental socio-economic status were associated with decreased risk.

CONCLUSIONS

Both biomedical and sociodemographic factors increase DCD risk. These findings can contribute to elucidating the origins of this disorder, and assist in the identification of children at risk for early referral and intervention.

Evaluation of the Psychometric Properties of the Portuguese Peabody Developmental Motor Scales-2 Edition: A Study with Children Aged 12 to 48 Months

The purpose of this study was to examine the psychometric properties of Peabody Developmental Motor Scales II (PDMS-2-Folio and Fewell, 2000) using a Portuguese sample. The validation of the Portuguese version of the PDMS-2 was applied according to the manual, for 392 children, from two institutions, from 12 to 48 months, with an analysis of the internal consistency (α Cronbach), of test–retest reliability (ICC) and construct validity (confirmatory factor analysis). The results of the confirmatory factorial analysis (χ2 = 55.614; df = 4; p = 0.06; χ2/df =13.904; SRMR (Standardized Root Mean Square Residual) = 0.065; CFI (Comparative Fit Index) = 0.99, TLI = 0.99, RMSEA (Root Mean Square Error of Approximation) = 0.068) of two factors (Gross Motor and Fine Motor) as the original version but correlated. Most of the subtests had good internal consistency (α = 0.85) and good test–retest stability (ICC = 0.98 to 0.99). The results indicated that the Portuguese version of the PDMS-2 is adequate and valid for assessing global and fine motor skills in children aged 12 to 48 months, and can be used as a reference tool by health and education professionals to assess motor skills and, thus, allowing to detect maladjustments, deficiencies or precocity, so that children can later receive appropriate intervention.

DNA methylome perturbations: an epigenetic basis for the emergingly heritable neurodevelopmental abnormalities associated with maternal smoking and maternal nicotine exposure†

Maternal smoking during pregnancy is associated with an ensemble of neurodevelopmental consequences in children and therefore constitutes a pressing public health concern. Adding to this burden, contemporary epidemiological and especially animal model research suggests that grandmaternal smoking is similarly associated with neurodevelopmental abnormalities in grandchildren, indicative of intergenerational transmission of the neurodevelopmental impacts of maternal smoking. Probing the mechanistic bases of neurodevelopmental anomalies in the children of maternal smokers and the intergenerational transmission thereof, emerging research intimates that epigenetic changes, namely DNA methylome perturbations, are key factors. Altogether, these findings warrant future research to fully elucidate the etiology of neurodevelopmental impairments in the children and grandchildren of maternal smokers and underscore the clear potential thereof to benefit public health by informing the development and implementation of preventative measures, prophylactics, and treatments. To this end, the present review aims to encapsulate the burgeoning evidence linking maternal smoking to intergenerational epigenetic inheritance of neurodevelopmental abnormalities, to identify the strengths and weaknesses thereof, and to highlight areas of emphasis for future human and animal model research therein.

Maternal smoking during pregnancy and intelligence quotient in offspring: A systematic review and meta-analysis

BACKGROUND

Exposure to tobacco during pregnancy may disrupt fetal brain development and impact offspring cognitive development.

AIMS

To perform a systematic review and meta-analysis on maternal smoking during pregnancy and intelligence quotient (IQ) in childhood, adolescence, and adulthood.

METHODS

We searched PubMed, Lilacs, PsycINFO, and Web of Science. Original articles evaluating tobacco use/exposure during pregnancy and the offspring's IQ as the outcome. The review protocol is registered in PROSPERO (number CRD 42,019,116,257). For the meta-analysis, we included studies with information on the regression coefficient and its confidence interval (CI) or standard error. Random effects model was used for pooling the estimates.

RESULTS

25 studies were included in the review, and of these 14 met the inclusion criteria for the meta-analysis. The overall pooled estimate showed that subjects who were exposed to maternal smoking during pregnancy presented lower IQ scores, compared to those not exposed to maternal smoking (β -1.30; 95 % CI -1.74, -0.86; I² = 87.8 %); IQ scores were also lower in crude (β -5.46; 95 % CI -7.31, -3.60; I²: 79.0 %) and adjusted pooled estimates (β =-0.45; 95 % CI -0.76, -0.13; I² = 80.4 %), for the group exposed to maternal smoking. In the stratified analysis, an inverse association was also observed in studies with large sample size (n≥1000 participants) (β=-0.49; 95 % CI -0.96, -0.02), among those performed with adolescents (β=-1.16; 95 % CI -2.18, -0.14), and among those adjusted for maternal education (β=-0.57; 95 % CI -1.05, -0.08).

CONCLUSIONS

Our findings suggest that exposure to tobacco during pregnancy may have negative effects on IQ. However, the findings of this meta-analysis should be interpreted with caution.

Childhood Exposure to Parental Smoking and Midlife Cognitive Function

We studied whether exposure to parental smoking in childhood/adolescence is associated with midlife cognitive function, leveraging data from the Cardiovascular Risk in Young Finns Study. A population-based cohort of 3,596 children/adolescents aged 3-18 years was followed between 1980 and 2011. In 2011, cognitive testing was performed on 2,026 participants aged 34-49 years using computerized testing. Measures of secondhand smoke exposure in childhood/adolescence consisted of parental self-reports of smoking and participants' serum cotinine levels. Participants were classified into 3 exposure groups: 1) no exposure (nonsmoking parents, cotinine <1.0 ng/mL); 2) hygienic parental smoking (1-2 smoking parents, cotinine <1.0 ng/mL); and 3) nonhygienic parental smoking (1-2 smoking parents, cotinine ≥1.0 ng/mL). Analyses adjusted for sex, age, family socioeconomic status, polygenic risk score for cognitive function, adolescent/adult smoking, blood pressure, and serum total cholesterol level. Compared with the nonexposed, participants exposed to nonhygienic parental smoking were at higher risk of poor (lowest quartile) midlife episodic memory and associative learning (relative risk (RR) = 1.38, 95% confidence interval (CI): 1.08, 1.75), and a weak association was found for short-term and spatial working memory (RR = 1.25, 95% CI: 0.98, 1.58). Associations for those exposed to hygienic parental smoking were nonsignificant (episodic memory and associative learning: RR = 1.19, 95% CI: 0.92, 1.54; short-term and spatial working memory: RR = 1.10, 95% CI: 0.85, 1.34). We conclude that avoiding childhood/adolescence secondhand smoke exposure promotes adulthood cognitive function.

Prenatal Exposure to Tobacco and Offspring Neurocognitive Development in the Healthy Start Study

OBJECTIVE

To explore the associations between prenatal exposure to tobacco and neurocognitive development, in the absence of prematurity or low birth weight.

STUDY DESIGN

We followed mother-child pairs within Healthy Start through 6 years of age. Children were born at ≥37 weeks of gestation with a birth weight of ≥2500 g. Parents completed the Third Edition Ages and Stages Questionnaire (n = 246) and children completed a subset of the National Institutes of Health Toolbox Cognition Battery (n = 200). The Ages and Stages Questionnaire domains were dichotomized as fail/monitor and pass. Maternal urinary cotinine was measured at approximately 27 weeks of gestation. Separate logistic regression models estimated associations between prenatal exposure to tobacco (cotinine below vs above the limit of detection) and the Ages and Stages Questionnaire domains. Separate linear regression models estimated associations between prenatal exposure to tobacco and fully corrected T-scores for inhibitory control, cognitive flexibility, and receptive language, as assessed by the National Institutes of Health Toolbox. A priori covariates included sex, maternal age, maternal education, daily caloric intake during pregnancy, race/ethnicity, household income, maternal psychiatric disorders, and, in secondary models, postnatal exposure to tobacco.

RESULTS

Compared with unexposed offspring, exposed offspring were more likely to receive a fail/monitor score for fine motor skills (OR, 3.9; 95% CI, 1.5-10.3) and decreased inhibitory control (B: -3.0; 95% CI, -6.1 to -0.7). After adjusting for postnatal exposure, only the association with fine motor skills persisted.

CONCLUSIONS

Prenatal and postnatal exposures to tobacco may influence neurocognitive development, in the absence of preterm delivery or low birth weight. Increased developmental screening may be warranted for exposed children.

Investigating the Association Between Exposure to Second Hand Smoke in utero and Developmental Coordination Disorder

Background: Developmental coordination disorder (DCD) and attention-deficit hyperactivity disorder (ADHD) are highly comorbid in children. There is evidence linking second hand smoke (SHS) exposure in utero to ADHD; however, it's relation to DCD is unknown. The purpose of this study was to examine the effect of SHS exposure in utero in children with and without DCD. Methods: This study was a cross-sectional examination of 122 children from the District School Board of Niagara (72 males, 50 females, M _age = 12.9 years) who were part of a larger, prospective cohort study. Participants were assessed for motor proficiency and intelligence and were screened for symptoms of ADHD using the Bruininks-Oseretsky Test of Motor Proficiency-Short Form, the Kaufman Brief Intelligence Inventory, 2nd edition, and the Conners' Parent Rating Scales-Revised: Short Form, respectively. Parent questionnaires were used to determine SHS exposure in utero as either yes or no. Multinomial logistic regression was used to examine the relationship between SHS exposure and DCD risk. Results: Children exposed to SHS in utero were significantly more likely to be at high risk for DCD than children who were not (OR = 3.33, p = 0.004), and children exposed to SHS in utero were more likely to be at moderate risk for DCD in the presence (OR = 3.57, p = 0.025) or absence of ADHD (OR = 2.38, p = 0.042). However, statistical adjustment for birth weight, socioeconomic status, age, and sex reduced this effect to non-significance in the moderate risk group. Conclusion: Results suggest exposure to SHS during pregnancy increases the chances of a child developing high risk DCD. While SHS exposure may increase DCD risk with and without ADHD, this effect may be explained by covariates and confounding factors. Further study is needed to examine the mechanisms linking SHS exposure in utero to motor coordination problems in children.

Maternal Cigarette Smoke Exposure Worsens Neurological Outcomes in Adolescent Offspring with Hypoxic-Ischemic Injury

Hypoxic-ischemic (HI) encephalopathy occurs in approximately 6 per 1000 term newborns leading to devastating neurological consequences, such as cerebral palsy and seizures. Maternal smoking is one of the prominent risk factors contributing to HI injury. Mitochondrial integrity plays a critical role in neural injury and repair during HI. We previously showed that maternal cigarette smoke exposure (SE) can reduce brain mitochondrial fission and autophagosome markers in male offspring. This was accompanied by increased brain cell apoptosis (active caspase-3) and DNA fragmentation (TUNEL staining). Here, we aimed to investigate whether maternal SE leads to more severe neurological damage after HI brain injury in male offspring. Female BALB/c mice (8 weeks) were exposed to cigarette smoke prior to mating, during gestation, and lactation. At postnatal day 10, half of the pups from each litter underwent left carotid artery occlusion, followed by exposure to 8% oxygen (92% nitrogen). At postnatal day 40-44, maternal SE reduced grip strength in grip traction and foot fault tests, which were also reduced by HI injury to similar levels regardless of the maternal group. Limb coordination was impaired by maternal SE which was not worsened by HI injury. Maternal SE increased anxiety level in the offspring, which was normalized by HI injury. Apoptosis markers were increased in different brain regions by maternal SE, with the cortex having further increased TUNEL by HI injury, along with increased markers of inflammation and mitophagy. We conclude that maternal SE can worsen HI-induced cellular damage in male offspring well into adolescence.

Early life events and motor development in childhood and adolescence: a longitudinal study

AIM

Few studies have reported on early life risk factors for motor development outcomes past childhood. Antenatal, perinatal and neonatal factors affecting motor development from late childhood to adolescence were explored. As sex differences in motor development have been previously reported, males and females were examined separately.

METHODS

Participants (n = 2868) were from the Western Australian Pregnancy Cohort Study. Obstetric and neonatal data were examined to determine factors related to motor development at 10 (n = 1622), 14 (n = 1584) and 17 (n = 1221) years. The Neuromuscular Development Index (NDI) of the McCarron Assessment of Motor Development determined offspring motor proficiency. Linear mixed models were developed to allow for changes in motor development over time.

RESULTS

Maternal pre-eclampsia, Caesarean section and low income were negatively related to male and female motor outcomes. Lower percentage of optimal birthweight was related to a lower male NDI. Younger maternal age, smoking during early pregnancy and stress during later pregnancy were related to lower female NDIs.

CONCLUSION

Events experienced during pregnancy were related to motor development into late adolescence. Males and females were influenced differently by antenatal and perinatal risk factors; this may be due to sex-specific developmental pathways.

Understanding sociodemographic and sociocultural factors that characterize tobacco use and cessation during pregnancy among women in the Dominican Republic

Tobacco use and exposure are serious public health problems that threaten to undermine improvements in maternal and child health, and add to already existing poor pregnancy outcomes in many low- and middle-income countries. The purpose of this study is to explore factors that characterize tobacco use and cessation during pregnancy among women in the Dominican Republic. This study was part of a larger trial and includes a sample of women who participated in baseline surveillance and community assessments (n = 613). Descriptive, bivariate, and multivariable analyses were conducted. Overall, 93.31 % (n = 572) of women experienced a past/current pregnancy and 22.44 % (n = 127) smoked during a past or current pregnancy. Among women who had smoked, 34.13 % (n = 43) stopped smoking due to a pregnancy, and 46.03 % (n = 58) were advised by a health care provider to quit smoking because of pregnancy. Women who were older, Catholic, and had a mother who used tobacco were three times more likely to smoke during a past or current pregnancy. Inability to read or write was also significantly associated with smoking during pregnancy. Women who were able to read and write and were from a tobacco growing community were three times more likely to quit smoking during pregnancy. This study provides a preliminary understanding of factors influencing tobacco use and cessation among pregnant women in the Dominican Republic. It also informs a critical area for public health research and intervention, indicating opportunities to engage the health care provider community in intervening with pregnant women and their families.

Secondhand Tobacco Smoke Exposure and Neuromotor Function in Rural Children

OBJECTIVE

To investigate the relationship between secondhand tobacco smoke (SHS) exposure and neuromotor function in children.

STUDY DESIGN

We studied 404 children aged 7-9 years who were exposed to SHS and other environmental neurotoxicants. Parents reported smoking habits, and serum cotinine levels were measured in children to determine SHS exposure. The Halstead-Reitan Finger Oscillation Test, Purdue Grooved Pegboard Test-Kiddie version, and Bruininks-Oseretsky Test of Motor Proficiency 2-Short Form were used to assess neuromotor function. Multivariable regression models that accounted for potential confounders were used to evaluate the associations.

RESULTS

Approximately 50% of the children were exposed to SHS based on serum cotinine measures. Exposure to SHS was significantly associated with motor impairment in children, including diminished visuomotor coordination (P = .01), fine motor integration (P = .01), balance (P = .02), and strength (P = .04) after adjusting for exposures to lead and manganese, age, sex, body mass index, measures of parental cognitive abilities, parental education, and quality of home environment.

CONCLUSION

SHS is a neurotoxicant that may be associated with impaired childhood neuromotor function.

Prenatal Second-Hand Smoke Exposure Measured with Urine Cotinine May Reduce Gross Motor Development at 18 Months of Age

OBJECTIVE

To evaluate the association of second-hand smoke exposure of pregnant mothers using urine cotinine with the neurodevelopment of their children at 18 months of age in the mother-child cohort in Crete (Rhea Study).

STUDY DESIGN

Selected participants were Greek mothers with singleton pregnancies, had never smoked, and had available urine cotinine measurements in pregnancy, and their children for whom a neurodevelopmental assessment was completed. We performed face-to-face interviews twice during pregnancy and postnatally, and assessed children's neurodevelopment at 18 months of age using the Bayley Scales of Infant and Toddler Development, Third Edition. We used linear regression and generalized additive models.

RESULTS

Of 599 mothers, 175 (29%) met the inclusion criteria. Maternal urine cotinine levels were low (mean: 10.3 ng/mL, SD: 11.7 ng/mL). Reported passive smoking from different sources was strongly associated with urine cotinine levels. A negative association was observed between cotinine levels in pregnancy and child's gross motor function (beta = -3.22 per 10 ng/mL, 95% CI -5.09 to -1.34) after adjusting for factors potentially associated with neurodevelopment; results were similar in both sexes. A negative association was also observed for cognitive and receptive communication scales but the effect was small and not statistically significant.

CONCLUSIONS

Maternal exposure during pregnancy to second-hand smoke measured through urine cotinine was associated with a decrease in gross motor function among 18-month-old children, even at low levels of exposure.

Regular moderate exercise during pregnancy does not have an adverse effect on the neurodevelopment of the child

AIM

Current U.S. guidelines suggest that pregnant women should exercise regularly during pregnancy, and we examined the neurodevelopment of the children whose mothers had taken that advice.

METHODS

This Norwegian study included 188 children whose mothers had followed a structured exercise protocol and 148 control children whose mothers had not. Their cognitive, language and motor skills were assessed at 18 months of age by the Bayley Scales of Infant Development-III and daily life functioning with the Ages and Stages Questionnaire.

RESULTS

No significant differences were found between the two groups. Subgroup analyses revealed that the children whose mothers had exercised had a slightly lower motor composite score (mean: 97.6, 95% CI: 96.0-99.2) than the control group (mean: 100.0, 95% CI: 98.6-101.5) (p = 0.03). Boys in the intervention group had lower fine motor scores (mean: 10.6, 95% CI: 10.3-11.0) than boys in the control group (mean: 11.5, 95% CI: 11.0-11.9) (p = 0.01).

CONCLUSION

Our main finding was that regular moderate exercise during pregnancy does not adversely affect neurodevelopment in children. The lower motor scores in the subgroup analyses are probably clinically insignificant, but the lower fine motor scores for boys in the intervention group warrant further research.

Determinants of developmental coordination disorder in 7-year-old children: a study of children in the Danish National Birth Cohort

AIM

The aim of this study was to investigate early life determinants of developmental coordination disorder (DCD) in 7-year-old children.

METHOD

The study was based on data from 33,354 women and their children who participated in the 7-year follow-up study of the Danish National Birth Cohort. Information on several potential determinants (maternal age at conception, maternal occupational status, smoking and alcohol consumption during pregnancy, child's sex, intrauterine growth restriction, degree of preterm birth, and age at walking) was obtained from population registries, from interviews during pregnancy and when the child was 18 months old. The outcome in this study was DCD at 7 years of age, measured by the validated Developmental Coordination Disorder Questionnaire. The associations between the potential determinants and DCD were estimated using logistic regression.

RESULTS

The study population consisted of 17,065 males and 16,289 females (141 [0.4%] born very preterm [23(+0)-31(+6) wk]; 1281 [3.8%] born moderately preterm [32(+0)-36(+6) wk]; 29,044 [87.1%] were born term [37(+0)-41(+6) wk], and 2888 [8.7%] were born post-term [≥ 42(+0) wk]). Independently of each other, the following determinants were predictors of DCD: being a female (odds ratio [OR] 0.36 [95% confidence interval {CI} 0.31-0.41]); being born very preterm (OR 6.28 [95% CI 3.99-9.89]) or moderately preterm (OR 2.10 [95% CI 1.65-2.67]); being small for gestational age (OR 1.74 [95% CI 1.46-2.08]); being 15 months of age or more at walking attainment (OR 3.05 [95% CI 2.57-3.60]); and maternal occupational status (higher grade professionals (OR 1.28 [95% CI 1.02-1.61); economically inactive (OR 1.43 [95% CI 1.07-1.91]). Young maternal age and smoking were risk factors among term-born children.

INTERPRETATION

The risk of DCD increases with decreasing gestational age. Intrauterine growth restriction is also a strong risk factor, as well as delayed walking.

Effects of tobacco smoking in pregnancy on offspring intelligence at the age of 5

The aim of the study was to examine the effects of tobacco smoking in pregnancy on children's IQ at the age of 5. A prospective follow-up study was conducted on 1,782 women, and their offspring were sampled from the Danish National Birth Cohort. At 5 years of age, the children were tested with the Wechsler Preschool and Primary Scale of Intelligence-Revised. Parental education, maternal IQ, maternal alcohol consumption in pregnancy, the sex and age of the child, and tester were considered core confounders, but the full model also controlled for prenatal paternal smoking, maternal age and Bodymass Mass Index, parity, family/home environment, postnatal parental smoking, breast feeding, the child's health status, and indicators for hearing and vision impairments. Unadjusted analyses showed a statistically significant decrement of 4 points on full-scale IQ (FSIQ) associated with smoking 10+ cigarettes per day compared to nonsmoking. After adjustment for potential confounders, no significant effects of prenatal exposure to tobacco smoking were found. Considering the indisputable teratogenic effects of tobacco smoking, these findings should be interpreted with caution. Still, the results may indicate that previous studies that failed to control for important confounders, particularly maternal intelligence, may be subject to substantial residual confounding.

Adverse effects of heavy prenatal maternal smoking on attentional control in children with ADHD

OBJECTIVE

Exposure to heavy maternal cigarette smoking in pregnancy and severe maternal psychosocial stress during pregnancy appear to be important risk factors for the development of ADHD. This study aimed to determine whether these perinatal risk factors were associated with neuropsychological deficits commonly seen in ADHD.

METHOD

We examined the effect of these two risk factors on measures of attentional control, motor inhibition, visual-motor integration, and fine motor coordination in a group of 81 children with ADHD, aged from 8 to 18 years. The neuropsychological battery included the Connors' Continuous Performance Test (CPT), the Stroop Color-Word Interference Test, the Beery Visual-Motor Integration Test, and the Purdue Pegboard Test.

RESULTS

Heavy maternal smoking during pregnancy was associated with slower reaction times (p < .002), and reaction time variability (p < .007) on the CPT.

CONCLUSIONS

This study suggests a persistent negative effect of heavy prenatal maternal smoking on attentional control in children with ADHD. Future studies should examine the neurobiological basis and determine the degree to which inherited genetic susceptibility factors contribute to this finding.

Longitudinal study of smoking cessation before pregnancy and children's cognitive abilities at 56 months of age

BACKGROUND

An inverse relationship exists between the rates of maternal smoking during pregnancy and children's cognitive abilities. The effect of maternal cessation of smoking before pregnancy on child's cognitive development is less clear.

AIMS

To study whether maternal cessation of smoking before pregnancy is associated with children's cognitive abilities.

STUDY DESIGN AND SUBJECTS

The original cohort included all 1535 live-born infants admitted to the neonatal wards during 1 year and 658 randomly recruited non-admitted infants. The present study sample comprised 1019 (68.2%) children of the original sample born at term and free of any major impairment followed up to 56 months.

OUTCOME MEASURES

Child's general reasoning, visual-motor integration, verbal competence, and language comprehension at 56 months of age.

RESULTS

The results showed that children whose mothers smoked >10 cigarettes per day before pregnancy but none during pregnancy, fared 12.07 (95% confidence interval [CI]: 4.07 to 20.08) and 11.23 (95% CI: 2.81 to 19.66) age-standardized points poorer in general reasoning and in language comprehension tests, respectively, than children of never-smokers. All results were adjusted for the sex, gestational age-adjusted birth weight, multiple/singleton pregnancy, birth order, preeclampsia, maternal diabetes, admission to neonatal ward, 5-minute Apgar score (<7), breastfeeding, parental level of education, maternal age, BMI at the end of pregnancy and single parenting.

CONCLUSIONS

Heavy smoking before pregnancy is associated with children's lower cognitive abilities even if the mother has quit smoking before pregnancy. Identification and intervention of heavy smoking women of fertile age would potentially improve not only their odds to become pregnant but also benefit the offspring's cognitive functioning.

Effect of birth weight, maternal education and prenatal smoking on offspring intelligence at school age

To examine the combined effect of birth weight, mothers' education and prenatal smoking on psychometrically measured intelligence at school age 1,822 children born in 1992-1999 and attending the first six grades from 45 schools representing all of the fifteen Estonian counties with information on birth weight, gestational age and mother's age, marital status, education, parity and smoking in pregnancy, and intelligence tests were studied. The scores of Raven's Standard Progressive Matrices were related to the birth weight: in the normal range of birth weight (>or=2500 g) every 500 g increase in birth weight was accompanied by around 0.7-point increase in IQ scores. A strong association between birth weight and IQ remained even if gestational age and mother's age, marital status, education, place of residence, parity and smoking during pregnancy have been taken into account. Maternal prenatal smoking was accompanied by a 3.3-point deficit in children's intellectual abilities. Marriage and mother's education had an independent positive correlation with offspring intelligence. We concluded that the statistical effect of birth weight, maternal education and smoking in pregnancy on offspring's IQ scores was remarkable and remained even if other factors have been taken into account.

Smoking in pregnancy: a risk factor for adverse neurodevelopmental outcome in preterm infants?

AIM

To assess whether smoking in pregnancy influences neurodevelopmental outcome at 2-years of age in preterm infants with a gestational age <32 weeks.

METHODS

Between January 2003 and December 2005 we prospectively enrolled 181 infants born alive between 23 and 32 weeks of gestation; 142 infants (78.5%) completed the follow-up visit. The association between candidate risk factors and delayed motor or mental development (Bayley Scales of Infant Development II; psychomotor or mental developmental index <85) was analysed by means of logistic regression analysis.

RESULTS

Low maternal age, smoking in pregnancy, low gestational age, low birth weight, small for gestational age, chronic lung disease, intracerebral haemorrhage, periventricular leucomalacia, and retinopathy of prematurity (stages 3 and 4) all were associated with an increased risk for delayed development (p < 0.05, each). Smoking in pregnancy, small for gestational age and chronic lung disease maintained significance in a multivariable analysis.

CONCLUSION

Smoking in pregnancy emerged as a risk predictor for adverse neurodevelopmental outcome in our study. Strategies to reduce smoking in pregnancy should be further endorsed.

The impact of maternal smoking on fast auditory brainstem responses

Deficits in auditory processing have been posited as one of the underlying neurodevelopmental consequences of maternal smoking during pregnancy that leads to later language and reading deficits. Fast auditory brainstem responses were used to assess differences in the sensory processing of auditory stimuli among infants with varying degrees of prenatal cigarette exposure. Maternal report of consumption of cigarettes and blood samples were collected in the hospital to assess exposure levels and participants were then seen at 6-months. To participate in the study, all infants had to pass the newborn hearing exam or a clinically administered ABR and have no known health problems. After controlling for participant age, maternal smoking during pregnancy was negatively related to latency of auditory brainstem responses. Of several potential covariates, only perinatal complications and maternal alcohol use were also related to latency of the ABR responses and maternal smoking level accounted for significant unique variance after controlling for these factors. These results suggest that the relationship between maternal smoking may lead to disruption in the sensory encoding of auditory stimuli.

Maternal cigarette smoking during pregnancy and cognitive performance in adolescence

BACKGROUND

The incidence of cigarette smoking during pregnancy remains high. Maternal smoking during pregnancy is known to be associated with cognitive and behavioural sequelae in childhood and adolescence. We assessed the relationship between maternal cigarette smoking during pregnancy and cognitive abilities in adolescent offspring (n = 503, 12- to 18-years old) using an extensive 6-h battery of tests.

METHODS

Non-exposed adolescents (controls) were matched to exposed adolescents (cases) by maternal education and school attended. Cognitive abilities were evaluated using a neuropsychological battery consisting of 33 tasks measuring verbal abilities, visuo-spatial skills, verbal and visual memory, processing speed, resistance to interference and motor dexterity.

RESULTS

We found no differences between cases and controls in any of the cognitive domains whether potential confounders were included in the model or not. In addition to maternal smoking during pregnancy, we also evaluated the effect of sex and age on the various cognitive abilities in this large adolescent sample and found that most of the abilities continue to improve during adolescence to the same extent in girls and boys, with several age-independent sex differences.

CONCLUSIONS

We found no effect of maternal cigarette smoking during pregnancy on cognitive abilities of the adolescent offspring when matching cases and controls by maternal education, the most common confounder of maternal cigarette smoking during pregnancy.

Hot and cool forms of inhibitory control and externalizing behavior in children of mothers who smoked during pregnancy: an exploratory study

This study examined whether children exposed to prenatal smoking show deficits in “hot” and/or “cool” executive functioning (EF). Hot EF is involved in regulation of affect and motivation, whereas cool EF is involved in handling abstract, decontextualized problems. Forty 7 to 9-year-old children (15 exposed to prenatal smoking, 25 non-exposed) performed two computerized tasks. The Sustained Attention Dots (SA-Dots) Task (as a measure of “cool” inhibitory control) requires 400 non-dominant hand and 200 dominant hand responses. Inhibitory control of the prepotent response is required for dominant hand responses. The Delay Frustration Task (DeFT) (as a measure of “hot” inhibitory control) consists of 55 simple maths exercises. On a number of trials delays are introduced before the next question appears on the screen. The extent of response-button pressing during delays indicates frustration-induced inhibitory control. Prenatally exposed children showed poorer inhibitory control in the DeFT than non-exposed children. A dose–response relationship was also observed. In addition, prenatally exposed children had significantly higher (dose-dependent) conduct problem- and hyperactivity-inattention scores. There were no significant group differences in inhibitory control scores from the SA-Dots. These results indicate that children exposed to prenatal smoking are at higher risk of hot but not cool executive function deficits.

Maternal smoking habits and cognitive development of children at age 4 years in a population-based birth cohort

BACKGROUND

Active maternal smoking during pregnancy has been associated with a higher risk of behavioural disorders in children, but a few cohort studies measuring smoking data prospectively have studied its specific effects on the cognitive abilities of pre-schoolers.

METHOD

A birth cohort was set up in Menorca Island in 1997 within the Asthma Multicenter Infants Cohort Study. A total of 420 (87% of those eligible) children had complete data for final analyses at age 4 years. Interviewer-administered questionnaires were completed by mothers during the third trimester of pregnancy and then every year up to age 4 years of their child. A standardized version of the McCarthy Scales of Children's Abilities (MCSA) was used to evaluate the child's motor and cognitive capabilities. Multivariable regressions were used with MCSA's assessed outcomes adjusting for: home location, maternal alcohol consumption, mother's social class and level of education during pregnancy, parity, marital status, father's education level, child's gender, birth weight and height, breastfeeding duration, passive smoking, school season, age during test administration and evaluator (psychologist).

RESULTS

A high global consistency in maternal smoking habits was found (total agreement = 88.7%). Maternal social class and education level were inversely associated with maternal smoking behaviour. Maternal smoking during pregnancy (in cig./day) was associated with a decrease (in points) of children's global cognitive score [beta = -0.60, (95% CI: -1.10; -0.09)]; as well as global cognitive sub-areas like verbal score [beta = -0.59, (95% CI: -1.11; -0.07)]; quantitative score [beta = -0.57, (95% CI: -1.08; -0.06)]; executive function score [beta = -0.71, (95% CI: -1.23; -0.20)]; and working memory score [beta = -0.46, (95% CI: -0.92; -0.01)].

CONCLUSION

Our findings suggest an association with maternal smoking during pregnancy and lowered cognitive development in children at age 4 years.

Is maternal education related to infant motor development?

PURPOSE

Because results of previous studies were inconclusive, our purpose was to examine the relationship between maternal education and infant neuromotor development in infants who are healthy and born at term.

METHOD

Secondary analysis of normative data derived through administration of the Harris Infant Neuromotor Test (HINT) to 412 Canadian infants was conducted. Infants were recruited from community-based infant programs, childcare facilities, and homes in five Canadian provinces. Inclusion criteria included: term birth (38-42 weeks), birth weight > or =2500 g, and no history of major prenatal, perinatal, or postnatal medical complications or maternal complications. Infants encompassed Canadian ethnic diversity as well as equal gender distribution at each of 10 monthly age intervals.

RESULTS

The analysis demonstrated that maternal education was only minimally associated with infant neuromotor development as measured by HINT total scores.

CONCLUSIONS

Our results confirmed other researchers' findings of no association between maternal education and infant motor development.

Impact of prenatal chlorpyrifos exposure on neurodevelopment in the first 3 years of life among inner-city children

OBJECTIVE

The purpose of this study was to investigate the impact of prenatal exposure to chlorpyrifos on 3-year neurodevelopment and behavior in a sample of inner-city minority children.

METHODS

As part of an ongoing prospective cohort study in an inner-city minority population, neurotoxicant effects of prenatal exposure to chlorpyrifos were evaluated in 254 children through the first 3 years of life. This report examined cognitive and motor development at 12, 24, and 36 months (measured with the Bayley Scales of Infant Development II) and child behavior at 36 months (measured with the Child Behavior Checklist) as a function of chlorpyrifos levels in umbilical cord plasma.

RESULTS

Highly exposed children (chlorpyrifos levels of >6.17 pg/g plasma) scored, on average, 6.5 points lower on the Bayley Psychomotor Development Index and 3.3 points lower on the Bayley Mental Development Index at 3 years of age compared with those with lower levels of exposure. Children exposed to higher, compared with lower, chlorpyrifos levels were also significantly more likely to experience Psychomotor Development Index and Mental Development Index delays, attention problems, attention-deficit/hyperactivity disorder problems, and pervasive developmental disorder problems at 3 years of age.

CONCLUSIONS

The adjusted mean 36-month Psychomotor Development Index and Mental Development Index scores of the highly and lower exposed groups differed by only 7.1 and 3.0 points, respectively, but the proportion of delayed children in the high-exposure group, compared with the low-exposure group, was 5 times greater for the Psychomotor Development Index and 2.4 times greater for the Mental Development Index, increasing the number of children possibly needing early intervention services.

Association of maternal smoking during pregnancy and infant neurobehavioral status

The association of maternal smoking during pregnancy with neurobehavioral status was examined in 344 Japanese infants. Based on a questionnaire, their mothers were classified into three groups, Nonsmokers, Exsmokers, and Smokers. The Neonatal Behavioral Assessment Scale was administered three days after birth. Among the three groups, on the seven clusters and their 28 behavioral subscales there were no significant differences. The infants of Smokers had lower scores than those of Exsmokers and Nonsmokers on two behavioral items, general tone and peak of excitement. General tone remained significant after adjustment for covariates.

Interrelations Between Maternal Smoking During Pregnancy, Birth Weight and Sociodemographic Factors in the Prediction of Early Cognitive Abilities

Maternal prenatal smoking, birth weight and sociodemographic factors were investigated in relation to cognitive abilities of 1544 children (aged 3.5 years) participating in the Québec Longitudinal Study of Children's Development. The Peabody Picture Vocabulary Test (PPVT) was used to assess verbal ability, the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R) block design test to assess visuospatial ability, and the Visually Cued Recall (VCR) task to assess short-term memory. Prenatal smoking was related to performance on the WPPSI-R, the PPVT, and the VCR, although it did not independently predict any cognitive ability after maternal education was taken into account. Birth weight was a more robust predictor of all outcome measures and independently predicted VCR-performance. Birth weight interacted significantly with family income and maternal education in predicting visuospatial ability, indicating a greater influence of birth weight under relatively poor socio-economic conditions. Parenting and family functioning mediated associations between maternal education/family income and cognitive task performance under different birth weight conditions, although there were indications for stronger effects under relatively low birth weight. We conclude that investigations of moderating and mediating effects can provide insights into which children are most at risk of cognitive impairment and might benefit most from interventions.

Prenatal exposure to cigarettes, alcohol, and coffee and the risk for febrile seizures

OBJECTIVE

Febrile seizure is a common type of seizure in childhood, probably caused by both genetic and early environmental factors. Little is known about the effect of environmental factors that operate in prenatal life, although the fetal brain may be particular vulnerable as a result of extensive brain growth and differentiation in this period. We evaluated the association between prenatal exposure to cigarettes, alcohol, and coffee and the risk for febrile seizures in 2 population-based birth cohorts.

METHODS

The Aarhus Birth Cohort consisted of 25,196 children of mothers who were scheduled to deliver at Aarhus University Hospital (1989-1996). The Aalborg-Odense cohort consisted of 10,400 children of women who attended antenatal care in Odense or Aalborg (1984-1987). Both cohorts were linked with the Danish National Hospital Register and followed until December 1998 with a complete follow-up. We extracted from medical records additional information on febrile seizures in children in the Aarhus Birth Cohort who were born between 1989 and 1992.

RESULTS

We found a slightly increased risk for febrile seizures in children who were exposed to 10 or more cigarettes per day in the Aarhus Birth Cohort, but the corresponding association was weak in the Aalborg-Odense cohort. We found no association between maternal alcohol and coffee consumption and the risk for febrile seizures. The results were similar for simple and complex febrile seizures.

CONCLUSIONS

Our data suggest that prenatal exposure to low to moderate levels of alcohol and coffee has no impact on the risk for febrile seizures, whereas a modest smoking effect cannot be ruled out.

Long term cognitive development in children with prolonged crying

BACKGROUND

Long term studies of cognitive development and colic have not differentiated between typical colic and prolonged crying.

OBJECTIVE

To evaluate whether colic and excessive crying that persists beyond 3 months is associated with adverse cognitive development.

DESIGN

Prospective cohort study. A sample of 561 women was enrolled in the second trimester of pregnancy. Colic and prolonged crying were based on crying behaviour assessed at 6 and 13 weeks. Children's intelligence, motor abilities, and behaviour were measured at 5 years (n = 327). Known risk factors for cognitive impairment were ascertained prenatally, after birth, at 6 and 13 weeks, at 6, 9, and 13 months, and at 5 years of age.

RESULTS

Children with prolonged crying (but not those with colic only) had an adjusted mean IQ that was 9 points lower than the control group. Their performance and verbal IQ scores were 9.2 and 6.7 points lower than the control group, respectively. The prolonged crying group also had significantly poorer fine motor abilities compared with the control group. Colic had no effect on cognitive development.

CONCLUSIONS

Excessive, uncontrolled crying that persists beyond 3 months of age in infants without other signs of neurological damage may be a marker for cognitive deficits during childhood. Such infants need to be examined and followed up more intensively.

Environmental factors associated with a spectrum of neurodevelopmental deficits

A number of environmental agents have been shown to demonstrate neurotoxic effects either in human or laboratory animal studies. Critical windows of vulnerability to the effects of these agents occur both pre- and postnatally. The nervous system is relatively unique in that different parts are responsible for different functional domains, and these develop at different times (e.g., motor control, sensory, intelligence and attention). In addition, the many cell types in the brain have different windows of vulnerability with varying sensitivities to environmental agents. This review focuses on two environmental agents, lead and methylmercury, to illustrate the neurobehavioral and cognitive effects that can result from early life exposures. Special attention is paid to distinguishing between the effects detected following episodes of poisoning and those detected following lower dose exposures. Perinatal and childhood exposure to high doses of lead results in encephalopathy and convulsions. Lower-dose lead exposures have been associated with impairment in intellectual function and attention. At high levels of prenatal exposure, methylmercury produces mental retardation, cerebral palsy and visual and auditory deficits in children of exposed mothers. At lower levels of methylmercury exposure, the effects in children have been more subtle. Other environmental neurotoxicants that have been shown to produce developmental neurotoxicity include polychlorinated biphenyls (PCBs), dioxins, pesticides, ionizing radiation, environmental tobacco smoke, and maternal use of alcohol, tobacco, marijuana and cocaine. Exposure to environmental agents with neurotoxic effects can result in a spectrum of adverse outcomes from severe mental retardation and disability to more subtle changes in function depending on the timing and dose of the chemical agent.

Does maternal smoking have a negative physiological effect on breastfeeding? The epidemiological evidence

BACKGROUND

Women who smoke are less likely to breastfeed their children than nonsmokers. It is thought that nicotine has a negative effect on breastmilk supply by suppressing prolactin levels. The aim of this review was to assess the epidemiological evidence that maternal smoking has a negative physiological effect on breastfeeding.

METHODS

The following data sources were searched: The Cochrane Library, Medline, CINAHL, Current Contents, Psychinfo, Sociological Abstracts and the Lactation Resource Centre (Australian Breastfeeding Association) using the key words "smoking" and "breastfeeding" or "infant feeding." The Journal of Human Lactation and Birth were hand searched.

RESULTS

Women who smoke are less likely to intend to breastfeed, less likely to initiate breastfeeding, and likely to breastfeed for a shorter duration than nonsmokers. Several studies have found a dose-response relationship between the number of cigarettes smoked each day and breastfeeding intention, initiation, and duration that persists after adjusting for confounding factors. In some population groups a high proportion of smokers breastfeed successfully.

CONCLUSIONS

The association between maternal smoking and lack of breastfeeding is consistent across different study designs in a range of countries. Given that women who smoke are less likely to intend to breastfeed, however, it cannot be assumed that the relationship between smoking and duration of breastfeeding is a physiological one. If smoking had a consistent negative physiological effect on lactation, one would not expect to see such wide variations in breastfeeding rates among women who smoke. Therefore, it is likely that psychosocial factors are largely responsible for the lower rates of breastfeeding found in women who smoke compared with those who do not.

Smoking during pregnancy and infantile colic

OBJECTIVE

To evaluate the association between maternal smoking during pregnancy and infantile colic (IC).

METHODS

A follow-up study of singleton infants delivered by Danish mothers at the Aarhus University Hospital from May 1991 to February 1992 and still living in the municipality of Aarhus at the age of 8 months was conducted. A total of 1820 mothers and their infants were included. Self-administered questionnaires were used to collect data on smoking, other lifestyle factors, and sociodemographic variables at 16 and 30 weeks of gestation and 8 months postpartum. IC was defined in the 8-month questionnaire and based on Wessel's criteria, except that we used only the crying criterion.

RESULTS

IC was seen in 10.8% of all infants. We observed a twofold increased risk of IC among infants whose mothers smoked 15 or more cigarettes per day during their pregnancy(relative risk: 2.1; 95% confidence interval: 1.4-3.2) or in the postpartum period (relative risk: 2.0; 95% confidence interval: 1.3-3.1). Women who smoked continuously during pregnancy and the postpartum period had a relative risk of 1.5 (95% confidence interval: 1.1-2.0) of having a infant with IC compared with women who did not smoke during this period. Adjustment for maternal age, parity, marital status, alcohol intake, birth weight, gestational age, breastfeeding, caffeine intake postpartum, and paternal smoking did not change the effect measures.

CONCLUSION

The results indicate that maternal smoking during pregnancy may increase the risk of IC.