Time Matters: Evaluating the clinical and infectious outcomes in Rupture of Membranes<12 hours vs 12-18 hours, at term: a retrospective study.

Abstract

Objectives To identify factors associated with intrapartum fever (IPF) and clinical chorioamnionitis in patients with term prelabor rupture of membranes (PROM) lasting <18h and to evaluate microbiological findings in chorioamniotic swab cultures from patients with IPF. Design A retrospective study. Participants/Materials A total of 6,828 patients with term PROM were included and categorized into: PROM <12h (n=5,745) and PROM 12-18h (n=1,083). Exclusion criteria included multiple gestations, fetal anomalies, and incomplete medical records. Setting Galilee Medical Center, a tertiary care hospital, between March 2020 and May 2024. Methods The primary outcome was clinical chorioamnionitis, diagnosed by intrapartum fever ≥38°C and ≥2 clinical signs. Secondary outcomes included maternal (delivery mode, IPF, postpartum complications) and neonatal (Apgar scores, NICU admission, early-onset sepsis) outcomes. Chorioamniotic swabs were obtained from patients with IPF for microbiological analysis. Statistical analysis included chi-square or Fisher's exact tests, Mann-Whitney U tests, relative risks (RRs) with 95% confidence intervals (CIs), and multivariate logistic regression to identify independent predictors of clinical chorioamnionitis and IPF. Results PROM 12-18h was associated with higher rates of clinical chorioamnionitis (3.9% vs. 2.3%, p=0.002; RR 1.73, 95% CI: 1.23-2.45) and IPF (4.8% vs. 2.3%, p<0.001; RR 2.13, 95% CI: 1.34-3.31) compared with PROM <12h. The risk of clinical chorioamnionitis increased progressively with PROM duration, reaching a maximal elevation between 16-18h (aRR 5.23, 95% CI 2.80-9.76, compared with PROM ≤4h). Vaginal delivery was less frequent (76.9% vs. 83.4%, p<0.001), whereas cesarean (16.2% vs. 11.4%, p<0.001) and vacuum-assisted delivery rates (6.9% vs. 5.2%, p=0.029) were higher with PROM 12-18h. Postpartum antibiotic administration was more common (4.1% vs. 1.7%, p<0.001), and postpartum hospitalization was longer (2.4 vs. 2.1 days, p=0.003), respectively. Neonates born after PROM 12-18h had higher rates of NICU admission (4.9% vs. 3.1%, p=0.003), sepsis workups (4.6% vs. 3.0%, p=0.007), and NICU antibiotic treatment (2.9% vs. 1.6%, p=0.003). Multivariate analysis identified parity as protective against chorioamnionitis (OR 0.38, 95% CI: 0.21-0.69, p=0.002) and IPF (OR 0.52, 95% CI: 0.31-0.89, p=0.017). Epidural analgesia increased the odds of IPF (OR 2.20, 95% CI: 1.61-3.90, p=0.048), while meconium-stained amniotic fluid was associated with higher odds of chorioamnionitis (OR 2.86, 95% CI: 1.45-5.63, p=0.002). Positive chorioamniotic swab cultures were more frequent in PROM 12-18h than PROM <12h (59.6% vs. 35.7%, p<0.001; RR 1.71, 95% CI: 1.42-1.91), with higher Enterobacteriaceae detection (26.9% vs. 12.6%, p=0.014, p=0.014). Among GBS-colonized patients, Enterobacteriaceae detection was higher than in GBS-negative patients (32.3% vs. 14.3%, p<0.001), while GBS detection rates were comparable. Limitations The retrospective design and lack of long-term maternal and neonatal follow-up limit causal inference. Conclusions PROM lasting 12-18h was associated with higher rates of maternal and neonatal infections compared with PROM<12h. These findings suggest that infection risk rises earlier than the conventional 18h threshold, raising important considerations regarding the timing and choice of intrapartum antibiotic prophylaxis. Further prospective studies are warranted to validate these findings and to determine optimal antibiotic protocols.