Outcome of pregnancy in relation to irregular and inconvenient work schedules

Abstract

The relation between irregular and inconvenient working hours and the outcome of pregnancy was studied among women employed at a hospital in Sweden some time between 1980 and 1984. A questionnaire was distributed to 807 women; 81% replied. The pregnancies were divided into six groups with respect to work schedules during pregnancy. A slightly, but not significantly, increased risk of miscarriage was found in women who worked irregular hours or rotating shifts compared with women who worked only during the day (RR = 1.44, 95% confidence interval 0.83-2.51). Infants of non-smoking mothers who worked irregular hours had significantly lower birth weights than infants of non-smoking women working day time only. This difference was largest at birth order 2+. Similar results were found for infants of this birth order whose non-smoking mothers worked evenings or rotating shift.