Night work has been associated with sleep disorders as well as cardiovascular, endocrinologic, metabolic and immunological disturbances as shown in this review. Several night shifts in a row and more than one night shift per week is associated with increased risk of pregnancy-related complications. A dose-response pattern has been shown between the number of night shifts during pregnancy and the risk of miscarriage, hypertensive disorders and sick leave. Individual risk assessment of pregnant night workers should focus on their general health, the intensity of night shifts and other adverse working conditions.