Postmaturity or prolonged pregnancy is an important obstetric problem. About 4% of all pregnancies go on beyond 42 weeks. In order to prevent perinatal mortality and morbidity due to postmaturity, pregnancies are monitored more closely after 42 weeks at secondary care level (= hospital based health care) and there is an aim to end the pregnancy. The characteristics and size of the group having an increased risk of perinatal mortality are not clear. This study attempts to gain insight in, through a randomized trial, on the one hand the determinants of physiological and pathological postmaturity, and on the other hand the efficacy of stripping of the membranes in the 41st week as a method to initiate labour.