Duration of labor induction in nulliparous women at term: how long is long enough?

We evaluated the relationship between duration of labor induction and successful vaginal delivery (VD) in nulliparous women at term. Nulliparous women with singleton pregnancies > or = 37 weeks who underwent labor induction at a single institution were studied. Exclusion criteria were nonvertex presentation, stillbirth, fetal chromosomal/structural abnormalities, spontaneous labor, and spontaneous rupture of membranes. VD rates and maternal/neonatal outcomes were evaluated and compared with respect to the duration from induction to delivery. Over the 1-year study period, 340 women met all criteria. Seventy-five percent achieved VD (n = 255), 40.6% of whom had rate of cervical dilation in active labor < 1.0 cm/hour. Women requiring cesarean delivery were more likely to have fetal acidemia, admission to the neonatal intensive care unit, chorioamnionitis, and endometritis. There was no association with prolonged induction to delivery intervals and adverse maternal/neonatal outcomes. In our population, only 5.7% of nulliparous women undergoing labor induction at term remain undelivered at 48 hours. Of women achieving VD, > 40% had rate of cervical dilation in active labor < 1.0 cm/hour.