Low-dose oral misoprostol vs. oxytocin in premature rupture of membranes at ≥ 36 weeks: a comparison of labor induction outcomes and postpartum hemorrhage risk

Premature rupture of membranes (PROM) at ≥ 36 weeks elevates intrauterine infection risks, making timely labor induction the preferred intervention. While oxytocin infusion remains the conventional approach, its efficacy proves suboptimal in cases with unfavorable cervical conditions. Oral low-dose misoprostol emerges as a promising solution. The primary objective of this study was to compare the general obstetric delivery information and outcomes following the administration of oxytocin infusion or oral low-dose misoprostol solution for labor induction in PROM at ≥ 36 weeks women with an unfavorable cervical condition. A retrospective cohort study was conducted at a tertiary general hospital in China from March 2020 to November 2024, comparing oxytocin infusion and oral administration of 25 µg misoprostol every 2 h for labor induction in PROM at ≥ 36 weeks women with a Bishop score < 6. A total of 622 mothers were enrolled, with 297 in the oxytocin group and 325 in the misoprostol group. The rates of vaginal delivery and failed induction of labor were comparable between the two groups. Moreover, the duration of first stage of labor time was shorter in the misoprostol group relative to that of the oxytocin group (9.2 ± 4.8 h vs. 10.3 ± 5.0 h, p = 0.03), as well as the duration of administration to vaginal delivery (22.0 ± 10.8 h vs. 24.4 ± 12.1 h, p = 0.03). The rate of vaginal delivery in 24 h was high following induction with oral misoprostol [61.2% (137/224) vs. 51.2% (103/201), p = 0.04]. Notably, the incidence of uterine hyperstimulation, fetal distress, or suspected intrauterine infection was not significantly different between the two groups; however, there was a markedly lower incidence of overall postpartum hemorrhage (PPH) [8.6% (28/325) vs. 17.8% (53/297), p < 0.001] and severe PPH following vaginal delivery [0.4% (1/224) vs. 3.5% (7/201), p = 0.02] observed in the misoprostol group. Logistic regression analysis revealed that misoprostol administration was negatively associated with the occurrence of PPH (aOR: 0.42; 95% CI: 0.23 ~ 0.76, p < 0.01). In this retrospective single-center study, oral low-dose misoprostol yielded similar effects as oxytocin infusion on labor induction in PROM at ≥ 36 weeks pregnancies with unfavorable cervix, with a potentially lower risk of PPH. Nevertheless, these findings need to be further investigated through prospective multicenter studies.