Objective: To evaluate whether the elective induction of labor in nulliparous women with an unfavorable cervix affects the cesarean delivery rate.
Methods: We conducted a randomized controlled trial at a tertiary care medical center. Nulliparous woman between 38 0/7 and 38 6/7 weeks of gestation who were least 18 years of age with a singleton gestation and a Bishop score of 5 or less were randomized to elective induction of labor or expectant management. The induction of labor group was induced within 1 week of enrollment but not before 39 0/7 weeks of gestation. The control group continued routine prenatal care with admission for labor or obstetric indication. The primary outcome was cesarean delivery. Assuming a 20% rate in women in a control group, 80% power, and a goal to detect a twofold increase to 40% in the induction of labor group, 162 patients were needed.
Results: From March 2010 to February 2014, 82 patients were randomly allocated to induction of labor and 80 to expectant management. Baseline characteristics were similar between groups. The cesarean delivery rate in the induction of labor group was 30.5% (25/82) compared with 17.7% (14/79) in the expectant management group (relative risk 1.72, 95% confidence interval 0.96-3.06).
Conclusion: In nulliparous women with a Bishop score of 5 or less, elective induction after 39 0/7 weeks of gestation compared with expectant management of pregnancy did not double the rate of cesarean delivery.
Clinical trial registraction: ClinicalTrials.gov, www.clinicaltrials.gov, NCT01076062.
Level of evidence: I.