OBJECTIVE To determine maternal and perinatal morbidity and the spontaneous labor rate beyond 41 weeks of gestation. METHODS Patients with uncomplicated pregnancy were recruited at 41 weeks and screened for fetal or maternal well-being. Following observation between 41 and 42 weeks, patients were randomized to either serial monitoring by cardiotocography and measurement of amniotic fluid index, or to immediate induction. Comparisons were made using the chi(2) test. Results after 42 weeks were analyzed according to intention at randomization. RESULTS Morbidity was not increased before 42 weeks. After 42 weeks, the cesarean section rate and incidence of meconium below the vocal cords were increased in monitored patients. The median gestational age in patients who were monitored was 298.5 (294-321) days. In patients observed from 41 weeks, 91.6% labored spontaneously. CONCLUSIONS It is reasonable to observe uncomplicated pregnancy until 42 weeks with adequate monitoring. After 42 weeks, induction of labor is preferred.