(820) Elective Induction of Trial of Labor after Cesarean at 39 weeks: Is it Risk Reducing?

Friday, February 10, 2023

10:30 AM – 12:00 PM

Objective: After the ARRIVE trial, induction of labor (IOL) at 39 weeks became ubiquitous. We aim to determine whether patients with a prior cesarean should undergo risk reducing induction of labor at 39 weeks or be expectantly managed beyond 39 weeks.

Study Design: We created a decision analytic model to compare two management strategies in patients with a prior cesarean: 1) IOL at 39 weeks, 2) expectant management beyond 39 weeks. Patients expectantly managed beyond 39 weeks could: experience stillbirth, undergo indicated induction, or reach 40 weeks. At 40 weeks, patients could be induced or expectantly managed. We assumed all patients would be induced if they reached 41 weeks. We further assumed that all patients would attempt a trial of labor after cesarean (TOLAC) and all patients undergoing TOLAC were at risk for uterine rupture; the risk of uterine rupture was varied by IOL versus spontaneous labor and gestational age. Adverse maternal outcomes considered were maternal death, hysterectomy, operative injury (bowel or bladder injury). Neonatal outcomes considered were stillbirth, neonatal death, and hypoxic ischemic encephalopathy. Baseline risk estimates for uterine rupture, adverse events associated with uterine rupture, failed TOLAC, and successful TOLAC were obtained from the literature. One-way and multi-way sensitivity analyses were performed to address uncertainties in baseline assumptions.

Results:

Within baseline assumptions, the model identified that IOL at 39 weeks resulted in fewer adverse maternal or neonatal events compared to expectant management and more vaginal deliveries (Table). The model is sensitive to the risk of uterine rupture associated with IOL at 39 weeks; if the incidence of uterine rupture exceeds 1.42% in those undergoing IOL at 39 weeks, the model favors expectant management. In Monte Carlo simulations, induction of labor was selected in 91.7% of simulations.

Conclusion: Risk-reducing IOL at 39 weeks should not be withheld from women undergoing TOLAC and, depending on the risk of uterine rupture, may be associated with more favorable outcomes than expectant management.

Primary & Presenting Author(s)

Lorie M. Harper, MD,MSCI (she/her/hers)
Associate Professor
University of Texas Dell Medical School
Austin, Texas, United States

Coauthor(s)

GM
George A. Macones, MD,MSCE
The University of Texas at Austin
Austin, Texas, United States
Molly J. Stout, MD,MSCI
University of Michigan
Ann Arbor, Michigan, United States