Nulliparas at Term with Premature Rupture of Membranes and an Unfavorable Cervix: Labor Induction with Prostaglandin or Oxytocin? A Retrospective Matched Case Study

Background: Induction of labor (IOL) in nulliparas with premature rupture of membranes (PROM) and an unfavorable cervix at term poses challenges. Our study sought to investigate the impact of prostaglandin E2 (PGE2) compared to oxytocin on the duration of IOL in this specific group of parturients. Methods: This was retrospective matched-case study. All nulliparas with term PROM who underwent induction between January 2006 to April 2023 at Shaare Zedek Medical Center were identified. Cases induced by either PGE2 or oxytocin were matched by the following criteria: (1) time from PROM to IOL; (2) modified Bishop score prior to IOL <= 5; (3) newborn birthweight; and (4) vertex position. The primary outcome was time from IOL to delivery. Results: Ninety-five matched cases were identified. All had a modified Bishop score <= 5. Maternal age (26 +/- 4.7 years old, p = 0.203) and gestational age at delivery (38.6 +/- 0.6, p = 0.701) were similar between the groups. Matched factors including time from PROM to IOL (23.5 +/- 19.2 versus 24.3 +/- 21.4 p = 0.780), birth weight of the newborn (3111 g versus 3101 g, p = 0.842), and occiput anterior position (present on 98% in both groups p = 0.687) were similar. Time from IOL to delivery was significantly shorter by 3 h and 36 min in the group induced with oxytocin than in the group induced with PGE2 (p = 0.025). Within 24 h, 55 (58%) of those induced with PGE2 delivered, compared to 72 (76%) of those induced with oxytocin, (p = 0.033). The cesarean delivery rates [18 (19%) versus 17 (18%)], blood transfusion rates [2 (2%) versus 3 (3%)], and Apgar scores (8.8 versus 8.9) were similar between the groups (PGE2 versus oxytocin, respectively), p >= 0.387. Conclusions: Induction with oxytocin, among nulliparas with term PROM and an unfavorable cervix, was associated with a shorter time from IOL to delivery and a higher rate of vaginal delivery within 24 h, with no difference in short-term maternal or neonatal adverse outcomes.