Maternal and Neonatal Outcomes in Nulliparous Participants Undergoing Labor Induction by Cervical Ripening Method

Objective: This study aimed to evaluate maternal and neonatal outcomes by method of cervical ripening for labor induction among low-risk nulliparous individuals. Study Design: This is a secondary analysis of a multicenter randomized trial of labor induction at 39 weeks versus expectant management in low-risk nulliparous participants. Participants undergoing cervical ripening for labor induction in either group were included. Participants were excluded for preripening membrane rupture, abruption, chorioamnionitis, fetal demise, or cervical dilation ≥3.5 cm. Cervical ripening was defined by the initial method used: prostaglandin only (PGE; referent), Foley with concurrent prostaglandin (Foley-PGE), Foley only (Foley), and Foley with concurrent oxytocin (Foley-oxytocin). Coprimary outcomes were adverse maternal and neonatal composites. Secondary outcomes included cesarean delivery and length of labor and delivery (L&D) stay. Multivariable analysis was used to adjust for patient characteristics. Results: Of 6,106 participants included in the trial, 2,376 (38.9%) met criteria for this analysis. Of these, 1,247 (52.4%) had cervical ripening with PGE, 290 (12.2%) had Foley-PGE, 385 (16.2%) had Foley, and 454 (19.1%) had Foley-oxytocin. The maternal composite outcome was similar among participants who received Foley-PGE (24.1%, adjusted relative risk [aRR] = 1.21, 95% confidence interval [CI]: 0.96-1.52), Foley (21.3%, aRR = 1.16, 95% CI: 0.92-1.45), or Foley-oxytocin (19.4%, aRR = 1.04, 95% CI: 0.83-1.29), compared with PGE (19.7%). The neonatal composite outcome was less frequent in participants who received the Foley-PGE (2.4%, aRR = 0.35, 95% CI: 0.16-0.75) or Foley (3.6%, aRR = 0.51, 95% CI: 0.29-0.89) but did not reach statistical significance for participants who received Foley-oxytocin (4.6%, aRR = 0.63, 95% CI: 0.40-1.01) compared with PGE only (6.8%). Participants who received Foley-PGE or Foley-oxytocin had a shorter L&D stay (adjusted mean difference = -1.97 hours, 95% CI: -3.45 to -0.49 and -5.92 hours, 95% CI: -7.07 to -4.77, respectively), compared with PGE. Conclusion: In term low-risk nulliparous participants, Foley alone or concurrent with PGE is associated with a lower risk of adverse neonatal outcomes than with PGE alone. Length of L&D stay was the shortest with concurrent Foley-oxytocin.