Maternal prenatal smoking and hearing loss among adolescents.

Importance: Although smoking and secondhand smoke exposure are associated with sensorineural hearing loss (SNHL) in children and adults, the possible association between prenatal smoke exposure and hearing loss has not been investigated despite the fact that more than 12% of US children experience such prenatal exposure each year.
Objective: To investigate whether exposure to prenatal tobacco smoke is independently associated with SNHL in adolescents.
Design: Cross-sectional data were examined for 964 adolescents aged 12 to 15 years from the National Health and Nutrition Examination Survey 2005-2006.
Participants: Participants underwent standardized audiometric testing, and serum cotinine levels and self-reports were used to identify adolescents exposed to secondhand smoke or active smokers.
Main Outcomes and Measures: Prenatal exposure was defined as an affirmative parental response to, "Did [Sample Person's Name] biological mother smoke at any time while she was pregnant with [him/her]?" Sensorineural hearing loss was defined as an average pure-tone hearing level more than 15 dB for 0.5, 1, and 2 kHz (low frequency) and 3, 4, 6, and 8 kHz (high frequency).
Results: Parental responses affirmed prenatal smoke exposure in 16.2% of 964 adolescents. Prenatal smoke exposure was associated with elevated pure-tone hearing thresholds at 2 and 6 kHz (P < .05), a higher rate of unilateral low-frequency SNHL (17.6% vs 7.1%; P < .05) in bivariate analyses, and a 2.6-fold increased odds of having unilateral low-frequency SNHL in multivariate analyses (95% CI, 1.1-6.4) after controlling for multiple hearing-related covariates.
Conclusions and Relevance: Prenatal smoke exposure is independently associated with higher pure-tone hearing thresholds and an almost 3-fold increase in the odds of unilateral low-frequency hearing loss among adolescents. These novel findings suggest that in utero exposure to tobacco smoke may be injurious to the auditory system.