Occupational noise exposure during pregnancy: a case control study.

The possible effects of occupational noise on human pregnancy were examined in a case-control study. The case groups consisted of 284 women with premature deliveries and of 299 women with full-term, low birth weight infants (below the 25th centile), each case having a matched pair. The whole material, all cases and controls included, comprised 1166 women. The percentage of employment in the whole material was 77.8; there were no differences between the case women and their controls. Rather few women (N = 26; 3.5%) reported occupational noise (greater than or equal to 81 dB; Leq(A)8h) during their pregnancies and our study revealed no significant difference between the cases (N = 14) and the controls (N = 12) with regard to noise exposure. Because of the small number of exposed women conclusions have to be drawn carefully. Nevertheless, noise cannot be regarded as a major risk for prematurity or low birth weight of human newborns in Finnish society. The women with reported noise exposure had significantly more inconvenience at work than other working women. They also had significantly more numerous and longer sick leaves than other working women.