UCSF

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.