Supplementary Material for: Early versus late amniotomy for induction of labor: a systematic review and meta-analysis of randomized controlled trials

Introduction: This study evaluated the efficacy and safety of early amniotomy, performed before the active phase of labor, versus late amniotomy, conducted during the active phase.
Methods: Six data sources were screened until April 2024 for relevant randomized controlled trials (RCTs). Outcomes were pooled using risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI) in fixed or random-effects models.
Results: Sixteen RCTs involving 3,378 patients were included. Four RCTs had a low risk of bias, and 12 had some concerns. There was no significant difference in cesarean section rates (RR=1.00, 95% CI [0.79, 1.27], p=0.99) or normal vaginal delivery (RR=1.01, 95% CI [0.93, 1.10], p=0.81) between early and late amniotomy. However, early amniotomy reduced time-to-delivery by 2.42 hours (95% CI: -3.06, -1.54, p<0.0001) but increased the risk of chorioamnionitis (RR=1.46, 95% CI [1.06, 2.01], p=0.02). There was no difference in other maternal or neonatal outcomes, including endometritis, maternal fever, postpartum hemorrhage, cord prolapse, uterine hyperstimulation, APGAR score, neonatal sepsis, NICU admission, or meconium-stained amniotic fluid
Conclusion: Early amniotomy significantly reduced time-to-delivery without increasing cesarean section rates but was associated with a higher risk of chorioamnionitis. Further research is needed to determine the optimal IOL protocol.