290 Lack of an association between prenatal nicotine exposure and offspring’s hearing

Abstract

Maternal smoking is hypothesized to contribute to childhood hearing dysfunction; data on laboratory proven exposure are limited. We aimed to test for an association between in-utero exposure to nicotine and infant hearing dysfunction. Secondary analysis of a multicenter randomized trial to prevent congenital CMV infection among gravidas with primary CMV infection. Monthly IVIG therapy did not influence rate of congenital CMV. Dyads with missing urine, fetal or neonatal demise, and those with infants diagnosed with a major congenital anomaly, congenital CMV infection, or with evidence of middle ear dysfunction were excluded. The primary outcome was neonatal hearing impairment in at least one ear defined as amplitudes on otoacoustic emissions (DPOAE) test below frequency-specific cutoff for ≥50% of the frequencies tested, assessed within 42 days of birth. Cotinine was measured via commercially available ELISA kits in maternal urine collected at enrollment and third trimester (mean GA 16.0 and 36.7 weeks respectively). Blinded personnel ran samples in duplicates. Maternal urine cotinine >5 ng/ml at either time point defined in-utero exposure to nicotine. Multivariable logistic regression included variables associated with the primary outcome (P <0.1) and with the exposure (P <0.05) in univariate analysis. Of 399 enrolled patients, 150 were included in this analysis; 46 had evidence of nicotine exposure (Table 1). The primary outcome occurred in 18 newborns; with 15.2% in tobacco-exposed infants versus 10.6% in non-exposed (OR 1.52, 95% CI 0.55 – 4.20). This association was similar when exposure was stratified as heavy (>100ng/ml, OR 1.54, 95% CI 0.45-5.29) or mild (5-100ng/ml, OR 1.49, 95% CI 0.38-5.92). There was no association between nicotine exposure and frequency-specific amplitudes. Findings remained statistically non-significant on multivariable analysis. We did not demonstrate that prenatal nicotine exposure is associated with hearing dysfunction assessed on DPOAE in newborns exposed to maternal CMV infection. Larger studies with long-term follow up are needed.View Large Image Figure ViewerDownload Hi-res image Download (PPT)