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

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.

A Meta-Analysis of Stressors from the Total Environment Associated with Children's General Cognitive Ability

General cognitive ability, often referred to as ‘general intelligence’, comprises a variety of correlated abilities. Childhood general cognitive ability is a well-studied area of research and can be used to predict social outcomes and perceived success. Early life stage (e.g., prenatal, postnatal, toddler) exposures to stressors (i.e., chemical and non-chemical stressors from the total (built, natural, social) environment) can impact the development of childhood cognitive ability. Building from our systematic scoping review (Ruiz et al., 2016), we conducted a meta-analysis to evaluate more than 100 stressors related to cognitive development. Our meta-analysis identified 23 stressors with a significant increase in their likelihood to influence childhood cognitive ability by 10% or more, and 80 stressors were observed to have a statistically significant effect on cognitive ability. Stressors most impactful to cognition during the prenatal period were related to maternal health and the mother’s ability to access information relevant to a healthy pregnancy (e.g., diet, lifestyle). Stressors most impactful to cognition during the early childhood period were dietary nutrients (infancy), quality of social interaction (toddler), and exposure to toxic substances (throughout early childhood). In conducting this analysis, we examined the relative impact of real-world exposures on cognitive development to attempt to understand the inter-relationships between exposures to both chemical and non-chemical stressors and early developmental life stages. Our findings suggest that the stressors observed to be the most influential to childhood cognitive ability are not permanent and can be broadly categorized as activities/behaviors which can be modified to improve childhood cognition. This meta-analysis supports the idea that there are complex relationships between a child’s total environment and early cognitive development.

Is breast feeding associated with offspring IQ at age 5? Findings from prospective cohort: Lifestyle During Pregnancy Study

OBJECTIVES

Breast feeding is associated with health benefits for both mother and child, but many studies focusing on neurodevelopment have lacked information on important confounders and few randomised trials exist. Our objective was to examine the influence of breast feeding on child IQ at 5 years of age while taking maternal IQ and other relevant factors into account.

DESIGN

Prospective observational study.

SETTING

Population-based birth cohort in Denmark.

PARTICIPANTS

We used data from The Lifestyle During Pregnancy Study 1782 mother-child pairs sampled from the Danish National Birth Cohort (n=101 042).

OUTCOME MEASURES

Child IQ was assessed at age 5 years by the Wechsler Primary and Preschool Scales of Intelligence-Revised. On the same occasion maternal intelligence was assessed by Wechsler Adult Intelligence Scale and Raven's Standard Progressive Matrices. Exposure data on duration of breast feeding (n=1385) were extracted from telephone interviews conducted when the child was 6 and 18 months, and analyses were weighted by relevant sampling fractions.

RESULTS

In multivariable linear regression analyses adjusted for potential confounders breast feeding was associated with child IQ at 5 years (categorical χ2 test for overall association p=0.03). Compared with children who were breast fed ≤1 month, children breast fed for 2-3, 4-6, 7-9 and 10 or more months had 3.06 (95% CI 0.39 to 5.72), 2.03 (95% CI -0.38 to 4.44), 3.53 (95% CI 1.18 to 5.87) and 3.28 (95% CI 0.88 to 5.67) points higher IQ after adjustment for core confounders, respectively. There was no dose-response relation and further analyses indicated that the main difference in IQ was between breast feeding ≤1 month versus >1 month.

CONCLUSIONS

Breastfeeding duration of 1 month or shorter compared with longer periods was associated with approximately three points lower IQ, but there was no evidence of a dose-response relation in this prospective birth cohort, where we were able to adjust for some of the most critical confounders, including maternal intelligence.

Cognitive function among schoolchildren in Lebanon: association with maternal alcohol drinking and smoking during pregnancy and domestic use of detergents and pesticides during childhood

To evaluate the relation between caregiver exposure to toxics during pregnancy and childhood and the child's cognitive function in Lebanese children. This was a cross-sectional study conducted on Lebanese students in public and private schools from November 2017 to May 2018, enrolling 464 children. A first linear regression, taking the Cattell total score as the dependent variable and taking sociodemographic characteristics and the family history of the child as independent variables, showed that higher age (Beta = 1.65) was significantly associated with higher cognition, whereas a history of eczema in any of the parents (Beta = -7.32) was significantly associated with lower cognition in the child. A second linear regression, taking the Cattell total score as the dependent variable and taking sociodemographic characteristics and the family history of the child, and the exposure to toxics as independent variables, showed that maternal alcohol intake during pregnancy (Beta = -1.07) and detergent mixing (Beta = -1.48) were significantly associated with lower cognition in the child. A third linear regression, taking the Cattell total score as the dependent variable and taking sociodemographic characteristics and the family history of the child, the exposure to toxics and the diseases in the child as independent variables, showed that maternal alcohol intake during pregnancy (Beta = -1.07) and detergent mixing (Beta = -1.45) were significantly associated with lower cognition in the child, whereas a history of eczema in the child before the age of 2 years (Beta = 8.72) was significantly associated with higher cognition in the child. This study is the first to examine the association of a child's prenatal exposure and their exposure during childhood to environmental toxicants with their cognitive function in Lebanon. We consider this study to be important as it shows the possible effect of cleaning products mixing and maternal alcohol consumption on cognitive functions among children in Lebanon.

Contributions of a Child's Built, Natural, and Social Environments to Their General Cognitive Ability: A Systematic Scoping Review

The etiology of a child’s cognitive ability is complex, with research suggesting that it is not attributed to a single determinant or even a defined period of exposure. Rather, cognitive development is the product of cumulative interactions with the environment, both negative and positive, over the life course. The aim of this systematic scoping review was to collate evidence associated with children’s cognitive health, including inherent factors as well as chemical and non-chemical stressors from the built, natural, and social environments. Three databases were used to identify recent epidemiological studies (2003–2013) that examined exposure factors associated with general cognitive ability in children. Over 100 factors were evaluated from 258 eligible studies. We found that recent literature mainly assessed the hypothesized negative effects of either inherent factors or chemical exposures present in the physical environment. Prenatal growth, sleep health, lead and water pollutants showed consistent negative effects. Of the few studies that examined social stressors, results consistently showed cognitive development to be influenced by both positive and negative social interactions at home, in school or the community. Among behavioral factors related to diet and lifestyle choices of the mother, breastfeeding was the most studied, showing consistent positive associations with cognitive ability. There were mostly inconsistent results for both chemical and non-chemical stressors. The majority of studies utilized traditional exposure assessments, evaluating chemical and non-chemical stressors separately. Collective evidence from a limited number of studies revealed that cumulative exposure assessment that incorporates multiple chemical and non-chemical stressors over the life course may unravel the variability in effect on cognitive development and help explain the inconsistencies across studies. Future research examining the interactions of multiple stressors within a child’s total environment, depicting a more real-world exposure, will aid in understanding the cumulative effects associated with a child’s ability to learn.

Obstetric care providers assessing psychosocial risk factors during pregnancy: validation of a short screening tool - the KINDEX Spanish Version

BACKGROUND

High levels of stress due to diverse psychosocial factors have a direct impact on the mothers' wellbeing during pregnancy and both direct and indirect effects on the fetus. In most cases, psychosocial risk factors present during pregnancy will not disappear after delivery and might influence the parent-child relationship, affecting the healthy development of the offspring in the long term. We introduce a short innovative prenatal assessment to detect psychosocial risk factors through an easy to use instrument for obstetrical medical staff in the daily clinical practice, the KINDEX Spanish Version.

METHODS

In the present study midwives and gynecologists interviewed one hundred nineteen pregnant women in a public health center using the KINDEX Spanish Version. Sixty-seven women were then randomly selected to participate in an extended standardized validation interview conducted by a clinical psychologist using established questionnaires to assesses current stress (ESI, PSS-14), symptoms of psychopathology (HSCL-25, PDS) and traumatic experiences (PDS, CFV). Ethical approval was granted and informed consent was required for participation in this study.

RESULTS

The KINDEX sum score, as assessed by medical staff, correlated significantly with stress, psychopathology and trauma as measured during the clinical expert interview. The KINDEX shows strong concurrent validity. Its use by medical staff in daily clinical practice is feasible for public health contexts. Certain items in the KINDEX are related to the respective scales assessing the same risks (e.g.PSS-4 as the shorter version of the PSS-14 and items from the ESI) used in the validation interview.

CONCLUSIONS

The KINDEX Spanish Version is a valid tool in the hands of medical staff to identify women with multiple psychosocial risk factors in public health settings. The KINDEX Spanish Version could serve as a base-instrument for the referral of at-risk women to appropriate psychosocial intervention. Such early interventions could prove pivotal in preventing undesirable mother-child relationships and adverse child development.