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Labor

Poster Session 4

(1015) The Effect of Latent-Phase Duration on Pregnancy Outcomes in Nulliparas Undergoing Induction of Labor: Meta-Analysis

Wednesday, February 14, 2024
1:00 PM – 2:30 PM  
Location: Prince George's Exhibit Hall CDE, Lower Atrium Level
Objective:

Failed induction of labor (IOL) is defined as failure to deliver or achieve active labor after an adequate period of oxytocin and rupture of membrane (ROM). Previous studies showed an association between adverse maternal outcomes and longer duration of oxytocin and rupture of membranes (ROM). However, neonatal outcomes were not well-described. We sought to perform a meta-analysis of studies that evaluated outcomes according to the duration of oxytocin and ROM.

Study Design:

Studies were included in the meta-analysis if they were observational studies that examined a cohort of nulliparous individuals undergoing IOL with cephalic presentation and singleton pregnancies at 36 weeks or greater. The primary outcome was admission to the neonatal intensive care unit (NICU). Secondary outcomes included rates of chorioamnionitis, endometritis, cesarean delivery, and postpartum hemorrhage (PPH). Outcomes were compared between individuals who remained in latent labor and those who exited the latent phase (active labor or delivered) at 6, 9, 12, 15, and 18 hours of oxytocin and ROM. Findings were summarized as relative risk (RR) with 95% confidence interval (CI) using the random effects model.

Results:

Of 1364 studies found on the initial search, 4 studies and 22,184 nulliparous individuals were included in the meta-analysis. Compared to individuals who exited the latent labor, those who remained in latent labor at 12, 15, and 18 hours after oxytocin and ROM had an increased risk of NICU admission (range of RR 1.48-1.82; Table 1). All adverse maternal outcomes were increased in those who remained in latent labor at all time points (6, 9, 12, 15, and 18 hours) except for endometritis and PPH which were not significantly different after 18 hours of oxytocin and ROM.

Conclusion: In nulliparous individuals undergoing IOL, adverse neonatal outcomes increase significantly after 12 hours in those who do not deliver or achieve active phase. A definition of failed IOL as failure to achieve active labor after 12 hours of oxytocin and ROM is appropriate to minimize adverse outcomes.