Objective: To investigate how the interval between membrane rupture and delivery affects the risk of neonatal sepsis and whether duration of labor influences the risk.
Methods: A registry study included 113,568 singleton infants born at term after a trial of labor (elective cesarean deliveries excluded). The incidence of a diagnosis of sepsis during the neonatal period was correlated to the interval between membrane rupture and delivery. Multiple logistic regression analysis was done with adjustments for maternal age, parity, infant gender, gestational age, birth weight, and duration of labor. Receiver operating characteristics curves were created to estimate the optimal cutoff of membrane rupture time associated with an increased risk of neonatal septicemia.
Results: The rate of neonatal sepsis was 0.3% at a membrane rupture to delivery interval below 6 hours, 0.5% at 6-18 hours, 0.8% at 18-24 hours, and 1.1% after 24 hours. The risk of neonatal sepsis increased independently and nearly linearly with duration of membrane rupture up to 36 hours, with an odds ratio of 1.29 for each 6-hour increase in membrane rupture duration. The risk also increased with birth weight, gestational age, primiparity, and male infant gender. Duration of labor was not an independent risk factor for neonatal sepsis. Receiver operating characteristics curve analysis revealed an area under the curve of 0.66, but a superior cutoff time limit for the risk of sepsis was not found.
Conclusion: The risk of neonatal sepsis increases with duration of membrane rupture in a linear fashion during the first 36 hours, independently of labor duration.
Level of evidence: II.