Duration of Prelabor Rupture of Membranes and Early-Onset Neonatal Sepsis: A Retrospective Cohort with Risk Model

Abstract

Prelabor rupture of membranes (PROM) is an established risk factor for early-onset neonatal sepsis (EONS), but the quantitative relationship between rupture-to-delivery latency and EONS in resource-constrained settings without universal group B streptococcus (GBS) screening is incompletely characterized, and contemporary data from southern Iraq are absent from the indexed literature. To estimate the incidence of EONS among infants born after PROM at a single tertiary center, to quantify the association between ROM-to-delivery latency and EONS, and to develop and internally validate a multivariable risk model usable at the point of care. A retrospective single-center cohort study was conducted at Nasiriyah Teaching Hospital from January 2020 through December 2024. Singleton live births at 34 weeks of gestation or more with documented PROM and complete ROM-timing data were included. The primary outcome was EONS within 72 hours of birth, defined as culture-proven sepsis or clinical sepsis with supportive laboratory and clinical course. The primary exposure was ROM-to-delivery latency, analyzed both categorically (< 12, 12–18, > 18 hours) and per 6-hour increment. Multivariable logistic regression identified independent predictors; discrimination was assessed by the area under the receiver operating characteristic curve (AUC) with 1,000-resample bootstrap internal validation, and reporting followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) and Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis (TRIPOD) statements. Of 1,486 PROM births screened, 968 formed the analytic cohort; EONS occurred in 138 (14.3%, 95% confidence interval [CI] 12.1–16.7%), of which 37 (26.8%) were culture-proven, predominantly Klebsiella species and GBS. ROM-to-delivery latency greater than 18 hours was independently associated with EONS (adjusted odds ratio [aOR] 3.42, 95% CI 2.11–5.54), with risk rising approximately linearly (aOR 1.27 per 6-hour increment, 95% CI 1.14–1.42). The combined model achieved AUC 0.84 (95% CI 0.80–0.88); bootstrap-corrected AUC was 0.82.  EONS risk rose progressively with ROM-to-delivery latency. A six-variable model identified high-risk newborns at the point of care and may inform surveillance and prophylaxis decisions where universal GBS screening is unavailable.