Artificial Versus Spontaneous Rupture of Membranes After Balloon Ripening: Implications for Maternal Infectious Outcomes

OBJECTIVES: To compare maternal infectious morbidity following artificial versus spontaneous rupture of membranes (ROM) after cervical ripening with a balloon catheter and oxytocin augmentation. Although amniotomy is commonly performed to shorten labor, evidence regarding its infectious consequences after mechanical cervical ripening remains limited and inconsistent. DESIGN: Retrospective cohort study including 1,115 term singleton pregnancies induced with a transcervical balloon catheter followed by oxytocin between January 2020 and May 2024. Participants were categorized according to mode of ROM: artificial (amniotomy) or spontaneous. Participants/Materials: Eligible participants were patients with term (≥37 weeks) singleton pregnancies undergoing induction with a balloon catheter and oxytocin. Exclusion criteria included multiple gestations, prelabor ROM, non-cephalic presentation, and major fetal anomalies. A total of 1,115 patients met the inclusion criteria. SETTING: The study was conducted at Galilee Medical Center, a tertiary referral hospital affiliated with the Azrieli Faculty of Medicine, Bar-Ilan University, Israel. Data were obtained from institutional medical records for deliveries between January 2020 and May 2024. Institutional review board approval was obtained, and informed consent was waived due to the retrospective design. METHODS: Clinical, obstetric, microbiological, and neonatal data were extracted from electronic records. The primary outcome was clinical chorioamnionitis. Secondary outcomes included intrapartum fever, microbiological findings, mode of delivery, and neonatal complications. Continuous variables were analyzed using Student's t-test and categorical variables using χ² or Fisher's exact test. Firth penalized logistic regression was performed to assess independent associations between ROM mode and outcomes, adjusting for potential confounders. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were reported. RESULTS: Among 1,115 patients, 725 (65%) underwent amniotomy and 390 (35%) experienced spontaneous ROM. Amniotomy was associated with higher rates of clinical chorioamnionitis (3.0% vs. 0.3%, p<0.001), intrapartum fever (7.4% vs. 1.5%, p<0.001), and positive chorioamniotic cultures (11.3% vs. 6.2%, p=0.005), particularly Enterobacteriaceae. Despite a shorter ROM-to-delivery interval (6.4 vs. 12.2 hours, p<0.001), amniotomy was associated with higher cesarean delivery rates (13.5% vs. 3.3%, p<0.001), including for non-reassuring fetal heart rate (9.2% vs. 1.5%, p<0.001). Neonatal outcomes did not differ between groups. In adjusted analyses, amniotomy remained independently associated with clinical chorioamnionitis (adjusted OR 8.51; 95% CI 2.17-78.46; p=0.001), intrapartum fever (adjusted OR 4.04; 95% CI 1.84-10.46; p<0.001), and cesarean delivery (adjusted OR 5.27; 95% CI 2.61-10.32; p<0.001). LIMITATIONS: The retrospective single-center design limits causal inference and generalizability. Residual confounding, provider-dependent decision-making, and lack of data on vaginal examinations may have influenced the findings. The study was underpowered to detect rare neonatal infectious outcomes. CONCLUSIONS: Artificial ROM following balloon catheter ripening was associated with increased maternal infectious morbidity and higher cesarean delivery rates, despite shortening labor duration. However, it is possible that, in some cases, amniotomy was performed in response to suspected fetal compromise in an attempt to expedite delivery. Therefore, causal relationships between amniotomy and the observed outcomes, including cesarean delivery, cannot be definitively established. These findings support a selective, individualized approach to ROM management and warrant further investigation in prospective studies.