Maternal smoking during pregnancy: impact on otoacoustic emissions in neonates

To determine the effect of maternal smoking during pregnancy on transient evoked otoacoustic emissions levels in neonates.

This was a cross-sectional study investigating neonates in the maternity ward of a university hospital in the city of São Paulo, Brazil. A total of 418 term neonates without prenatal or perinatal complications were evaluated. The neonates were divided into two groups: a study group, which comprised 98 neonates born to mothers who had smoked during pregnancy; and a control group, which comprised 320 neonates born to mothers who had not. In order to compare the two ears and the two groups in terms of the mean overall response and the mean transient evoked otoacoustic emissions in response to acoustic stimuli delivered at different frequencies, we used analysis of variance with repeated measures.

The mean overall response and the mean frequency-specific response levels were lower in the neonates in the study group (p<0.001). The mean difference between the groups was 2.47 dB sound pressure level (95% confidence interval: 1.47-3.48).

Maternal smoking during pregnancy had a negative effect on cochlear function, as determined by otoacoustic emissions testing. Therefore, pregnant women should be warned of this additional hazard of smoking. It is important that smoking control be viewed as a public health priority and that strategies for treating tobacco dependence be devised.