Noise exposure during pregnancy and hearing in children

Study

© Emily Cahal - sxc.hu

A new cohort study has shown that noise exposure during pregnancy can damage the unborn child’s hearing, with an 80% increased risk in noisy occupational environments.

Until recently, it was assumed that unborn children where shielded from noise in the womb but it has been demonstrated that loud noise does in fact reach the fetus. The study carried out by the Institute of Environmental Medicine (IMM) at Karolinska Institutet, Stockholm, Sweden provides new evidence that women should avoid exposure to high levels of noise while they are pregnant.

The study, to be published in the journal Environmental Health Perspectives, included a cohort of over 1.4 million children born in Sweden between 1986 and 2008. Data collected included their mother’s occupation, smoking habits, age, ethnicity, body mass index, leave of absence, and socio-economic factors. Results showed that for the group of part-time and full-time workers, the adjusted hazard ratio (HR) for hearing dysfunction associated with maternal occupational noise exposure greater than 85 dB versus less than 75 dB was 1.27 (95% CI). For full-time workers as a group, the HR was 1.82 (95% CI).

“The Swedish Work Environment Authority recommendation is that pregnant women should avoid noise levels of over 80 dBA, but unfortunately this recommendation is not always followed,” says Jenny Selander, lead author for the study. “Our study shows how imperative it is for employers to observe this recommendation. Even if pregnant women themselves use ear protectors in noisy environments, the babies they’re carrying remain unprotected.”

Source: Karolinska Institutet; Selander J, et al. Maternal Occupational Exposure to Noise during Pregnancy and Hearing Dysfunction in Children: A Nationwide Prospective Cohort Study in Sweden. Environmental Health Perspectives 2015 Dec 8.

C.S.