Exposure to parental smoking and child growth and development: a cohort study

Abstract

Background: Studies on adverse childhood health and development outcomes associated with parental smoking have shown inconsistent results. Using a cohort of Belarusian children, we examined differences in cognition, behaviors, growth, adiposity, and blood pressure at 6.5 years according to prenatal and postnatal exposure to parental smoking.

Methods: Using cluster-adjusted multivariable regression, effects of exposure to prenatal smoking were examined by comparing (1) children whose mothers smoked during pregnancy with those of mothers who smoked neither during nor after pregnancy and (2) children whose mothers smoked during and after pregnancy with those whose mothers smoked after pregnancy only; effects of postnatal smoking were examined by comparing (1) children whose mothers smoked after pregnancy only with those of mothers who smoked neither during nor after pregnancy and (2) children whose fathers smoked with those whose fathers did not smoke among children of non-smoking mothers after adjusting for a wide range of socioeconomic and family characteristics.

Results: After adjusting for confounders, children exposed vs unexposed to prenatal maternal smoking had no differences in mean IQ, teacher-rated behavioral problems, adiposity, or blood pressure. Children exposed to maternal postnatal smoking had slightly increased behavioral problems [0.9, 95% CI: 0.6, 1.2 for total difficulties], higher body mass index [0.2, 95% CI: 0.1, 0.3], greater total skinfold thickness [0.4, 95% CI: 0.04, 0.71], and higher odds of overweight or obesity [1.4, 95% CI; 1.1, 1.7]. Similar magnitudes of association were observed with postnatal paternal smoking.

Conclusions: No adverse cognitive, behavioral and developmental outcomes were associated with exposure to maternal prenatal smoking. Observed associations with postnatal smoking of both parents may reflect residual confounding by genetic and family environmental factors.

Figure 1

Adjusted* mean differences in child neurobehavioral outcomes at age 6.5 years by exposure to prenatal and postnatal parental smoking. (a) Full-scale IQ. (b) Total difficulties. (c) Externalizing behaviors. (d) Internalizing behaviors. * Partial adjustment model controlled for cluster, child sex and age at outcome measures; full model additionally adjusted for maternal and paternal age, height, education, and occupation, marital status of parents at birth, birth order, maternal drinking during pregnancy, and paternal smoking at 6.5 years age (for maternal smoking only).

Figure 2

Adjusted* associations of exposure to prenatal and postnatal parental smoking with child anthropometric measures and blood pressure at age 6.5 years. (a) Height. (b) BMI. (c) Total (triceps + subscapular) skinfold thickness. (d) Overweight/obesity. (e) Systolic blood pressure. (f) Diastolic blood pressure. * Partial adjustment model controlled for cluster, child sex and age at outcome measures; full model additionally adjusted for maternal and paternal age, height, BMI, education, and occupation, marital status of parents at birth, birth order, maternal drinking during pregnancy, and paternal smoking at 6.5 years age (for maternal smoking only).