Benefits and risks of induction of labor at 39 or more weeks in uncomplicated nulliparous women: a retrospective, observational study

OBJECTIVE: To critically compare the benefits and risks of labor induction versus spontaneous labor in uncomplicated nulliparous women at 39 or more weeks of gestation. METHODS: We conducted a retrospective, observational study of 237 nulliparous women who were at 39 or more weeks of a singleton pregnancy with vertex presentation and intact membranes. We compared maternal outcomes including the Cesarean section rate and neonatal outcomes in the induced labor and spontaneous labor groups. RESULTS: Among the 237 women, 199 delivered vaginally (84.0%). The spontaneous labor group and induced labor group had a similar incidence of Cesarean delivery (17.7% vs. 12.3%, P=0.300). The length of stay and blood loss during delivery were also similar between the groups (4.3±1.5 vs. 3.9±1.5 days and 1.9±1.3 vs. 1.8±1.0 mg/sL, respectively; all P>0.05). Regarding neonatal outcomes, the rate of meconium-stained amniotic fluid, Apgar score <7 at 5 minutes, and intubation rate were similar between the groups (18.9% vs. 24.7%, 7.9% vs. 4.1%, and 6.1% vs. 4.4%, respectively, all P>0.05). Only the neonatal intensive care unit admission rate was significantly lower in the induction group than in the spontaneous labor group (28.0% vs. 13.2%, P=0.001). CONCLUSION: Maternal adverse outcomes of labor induction at 39 weeks of gestation were similar to those in a spontaneous labor group in uncomplicated nulliparous women. Neonatal adverse events were also similar between the groups. It may be acceptable to schedule labor induction as long as 7 days before the estimated date, even when the indication is only relative.