Abstract
OBJECTIVE: To determine whether prenatal and childhood tobacco smoke exposure (TSE) are each independently associated with mild sleep-disordered breathing (SDB) symptoms throughout early childhood, and whether the association between childhood TSE and SDB differs according to the level of prenatal exposure. METHODS: Longitudinal cohort study, using data from the Avon Longitudinal Study of Parents and Children, a population-based birth cohort from the United Kingdom. Primary exposures were repeated measures of mother-reported prenatal and childhood TSE through age 7 years. Outcomes were mother-reported measures of mild SDB symptoms, including snoring, mouth breathing, and witnessed apnea, repeated annually through age 7 years. RESULTS: A total of 12,030 children were followed for a median duration of 7 years. About 24.2% were exposed to prenatal tobacco smoke, 46.2% were exposed at least once in childhood, and 20.6% were exposed during both periods. Both prenatal and childhood TSE were associated with SDB symptoms throughout early childhood (adjusted OR [aOR] for any prenatal TSE 1.23; 95% confidence interval [CI] 1.08, 1.40; aOR for any childhood TSE 1.17; 95% CI 1.06, 1.29). We observed a dose-response effect between TSE and SBD symptoms, and found evidence of effect modification for those exposed during both time periods (combined high level exposure both prenatally and during childhood: aOR snoring 2.43 [95% CI 1.50, 3.93], aOR apnea 2.65 [95% CI 1.46, 4.82]). CONCLUSIONS: Prenatal and childhood TSE were both independently associated with mild SDB symptoms throughout early childhood in a dose-dependent manner, further supporting the critical importance of maintaining a tobacco-free environment throughout gestation and childhood.