In Denmark 30% of females in the reproductive age regularly have shift work. 22 epidemiological papers were studied looking at associations between shift work and abortion, stillbirth, preterm birth, and birth weight. No convincing associations were observed between rotating shift work or fixed nightshift and negative pregnancy outcome. Some epidemiological support was found for a relation between fixed nightshift and late abortions/stillbirth. If fixed night work for all pregnant women is avoided, seven late abortion/stillbirths a year can be prevented. Fixed night work for pregnant women should be avoided.