Prenatal and Secondhand Tobacco Smoke Exposures and Bronchitic Symptoms in Children and Adolescents

Abstract

RATIONALE: Because the effects of prenatal and secondhand (SHS) tobacco smoke exposures on bronchitic symptoms in children and adolescent have not been studied extensively, we evaluated these associations among 12,033 subjects (5-18 years) who participated in the southern California Children's Health Study in 1993-1996 and in 2003. METHODS: At study entry, bronchitic symptoms during the previous year was determined based on parental report of a daily cough for 3 months in a row, congestion or phlegm for at least 3 months in a row, or bronchitis. Information on maternal smoking during pregnancy, lifetime history of SHS exposure, number of household smokers (none, 1, 2 or more) and number of cigarettes smoked/day at home (none, <10, and ≥10) was based on parental report at cohort entry. We computed adjusted odds ratios (ORs) and 95% confidence intervals (CIs) controlling for potential confounders. Because bronchitic symptoms were common in subjects with asthma, we further evaluated these associations among subjects without asthma. RESULTS: Exposures to maternal smoking in utero was associated with increased risk of bronchitic symptoms (OR=1.18; 95% CI: 1.02-1.36). The risk of bronchitic symptoms increased significantly with increasing number of household smokers and number of cigarette smoked/day (both P-trend=0.02). These findings remained unchanged after restricting the analyses to subjects without asthma. CONCLUSIONS: Both in utero and secondhand tobacco smoke exposures increase the risk of bronchitic symptoms in children and adolescents. The findings, which have clinical and public health implications, highlight the need for implementing preventive interventions to reduce tobacco smoke exposures in all children and adolescents.