Prenatal tobacco exposure and the risk of conduct disorder symptoms in offspring at the age of 14 years: Findings from the Raine Study

Background: Emerging epidemiological evidence suggests that offspring born to mothers who smoked tobacco during pregnancy may have elevated risk of developing conduct disorder (CD) symptoms. We examined associations between maternal and paternal tobacco smoking during pregnancy and CD symptoms in offspring at the age of 14 years. Methods: We obtained data from the Raine Study, a multi-generational cohort study based in Western Australia. DSM-oriented scale of the Child Behavior Checklist (CBCL) was used to measure CD symptoms in offspring. Negative binomial regression was used to estimate the rate ratio (risks) (RR) of CD symptoms in offspring. We also produced the E-values to investigate the extent of unmeasured confounding. Paternal smoking during pregnancy was used as a proxy for environmental tobacco smoke exposure. Results: Complete data were available for 1747 mother-offspring and 1711 father-offspring pairs. After adjusting for potential confounders, we found elevated risks (rates) of CD symptoms in offspring born to mothers smoking tobacco during the first trimester [RR 1.52 (95 % CI: 1.24-1.87)], third trimester [RR 1.36 (95 % CI: 1.09-1.69)] and during both trimesters of pregnancy [RR 1.50 (95 % CI: 1.19-1.90)]. The rates of CD symptoms in offspring increased with the level of exposure to maternal smoking during pregnancy. However, we noted insufficient statistical evidence for an association between paternal smoking during pregnancy and CD symptoms in offspring. Conclusion: The associations we found for maternal but not paternal smoking may suggest a biological mechanism for intrauterine tobacco exposure on the risk of CD symptoms in offspring. Early interventions assisting pregnant mothers to quit tobacco smoking, or avoid smoking initiation, have potential to contribute health benefits to both mothers and their offspring.