Smoking cessation in pregnancy and the risk of child behavioural problems: a longitudinal prospective cohort study

Background The aim of this study was to examine the influence of smoking in pregnancy on child and adolescent behavioural development, in comparison with mothers who ceased smoking in the first 18 weeks of pregnancy and with those who never smoked, in a large prospective pregnancy cohort. Methods The Western Australian Pregnancy Cohort (Raine) Study provided comprehensive data from 2900 pregnancies. Smoking was assessed at 18 weeks gestation, and children were followed up at ages 1, 2, 3, 5, 8, 10 and 14 years. The Child Behaviour Checklist (CBCL) was used to measure problem child behaviour with continuous z-scores and clinical cut points at ages 2, 5, 8, 10 and 14 years. Potential confounders included maternal and family sociodemographic characteristics and alcohol exposure. Results After adjusting for confounders, children of light smokers who quit smoking by 18 weeks gestation had significantly lower CBCL total z-scores, indicative of better behaviour, than children of women who never smoked, children of heavy smokers who quit and continuing smokers. Maternal smoking during pregnancy resulted in higher CBCL total, internalising and externalising scores and a higher risk of clinically meaningful behaviour problems in children from ages 2 to 14. Conclusion The maternal decision not to quit smoking, or the inability to quit smoking, during pregnancy appears to be a particularly strong marker for poor behavioural outcomes in children. There is a need for a greater understanding of the psychosocial characteristics associated with the decision and ability to quit smoking in pregnancy.