Exposure to secondhand tobacco smoke and child behaviour - results from a cross-sectional study among preschool children in Bavaria

Aim: To evaluate the association of postnatal exposure to secondhand tobacco smoke on childhood behavioural problems after taking maternal smoking during pregnancy into account. Methods: In a cross-sectional survey of preschool children in Bavaria, exposure to secondhand tobacco smoke in the child's home was assessed via a parent questionnaire. The Strength and Difficulties Questionnaire (SDQ) was applied to assess child's behaviour. The association with secondhand tobacco smoke exposure was assessed for 'probable' outcomes of the problem subscales and of prosocial behaviour. Results: Among 5494 children (48% female), the SDQ indicated behavioural problems in up to 11%. After adjustment for socioeconomic factors, low birth weight and maternal smoking before and during pregnancy, a dose-response relationship with exposure to secondhand tobacco smoke was observed regarding hyperactivity/inattention (odds ratio compared to 'none' was 1.35 for 'low/medium' and 2.39 for 'high' exposure, 95% confidence intervals 1.02-1.78 and 1.62-3.53, respectively) as well as for conduct problems (OR 1.68 (1.37-2.06) and 1.93 (1.39-2.68)). Conclusion: Secondhand tobacco smoke exposure at home appears to be associated with an increased risk of behavioural problems among preschool children. Prevention of behavioural problems may be a further reason to target secondhand tobacco smoke exposure in children.