(1106) Association Between Artificial Rupture of Membranes and Labor Outcomes in Second-Trimester Induction of Labor

Objective:
To evaluate the association between artificial rupture of membranes (AROM) and labor duration in second-trimester induction of labor (2T IOL). Secondary objectives included evaluating associations between AROM and morbidity.

Study Design:

We conducted a retrospective cohort study of individuals undergoing 2T IOL at four academic hospitals from 2009–2019. Patients with twin gestations, preterm labor, cervical insufficiency, or rupture of membranes were excluded. The primary outcome was labor duration, defined as hours from first misoprostol dose to fetal expulsion. Secondary outcomes included a composite morbidity measure (suspected chorioamnionitis, blood transfusion, ICU admission, uterine rupture, readmission within 6 weeks, or death) and each complication individually. Labor duration was analyzed using linear regression and Cox survival modeling. Bivariate analysis identified no confounders, so final models were unadjusted. Secondary outcomes were assessed using regression analysis.

Results:

Among 681 patients meeting inclusion criteria, 81 (11.9%) underwent AROM. The groups differed only by induction methods. AROM was associated with significantly longer labor (mean 16.14 vs. 13.51 hours, p = 0.02). In unadjusted Cox modeling, AROM was associated with increased time to delivery (HR 0.76, 95% CI 0.60–0.96), confirmed by Kaplan-Meier analysis (log-rank p < 0.001). AROM was associated with increased composite morbidity (RR 1.52, 95% CI 1.14–2.02), primarily driven by suspected chorioamnionitis (RR 1.88, 95% CI 1.22–2.89).

Conclusion:

In patients undergoing 2T IOL, AROM was associated with an average increase in labor duration of 2.63 hours, a 52% increase in composite morbidity, and an 88% increased risk of suspected intraamniotic infection. These findings suggest AROM may contribute to prolonged labor and increased risk of infection in 2T IOL, warranting cautious clinical use.