Objective.To compare maternal and neonatal outcomes after 12 or 24 hours of expectant management in healthy nulliparous women with a ripe cervix and PROM at term.Design.A prospective, randomized study.Location.Karolinska Hospital, Stockholm. Sweden.Subjects.Two hundred and five healthy nulliparous women with singleton pregnancies, cephalic presentation, gestational duration 36 to 42 weeks, randomized to 12 or 24 hours of expectant management after evaluation of the cervical score (>5). If spontaneous labor did not occur, induction was performed with oxytocin after 12 or 24 hours, respectively. Main parameters. Maternal early morbidity and neonatal infections, obstetric intervention rate (cesarean section or instrumental delivery).Results.The cesarean section rate was 4% in each group. The vacuum extraction rate was 21% in each group. Induction of labor was performed in 47% of the women allocated to 12 hours of expectant management vs 17% of the women allocated to 24 hours of expectant management (p<0.05). The maternal morbidity rate was almost negligible. Only a few fetal infections occurred and no difference was noted between the groups.Conclusions.In healthy nulliparous women at term with a ripe cervix, expectant management over 24 hours vs 12 hours resulted in fewer inductions of labor and no increase in instrumental deliveries, without any increase in neonatal or maternal morbidity.