Length of rupture of membranes in the setting of premature rupture of membranes at term and infectious maternal morbidity.

OBJECTIVE: This study was undertaken to define the time thresholds of increased risk for infectious maternal morbidities with relationship to length of ruptured membranes at term.

STUDY DESIGN: We designed a retrospective cohort study of all women with premature rupture of membranes beyond 37 weeks' gestation at a single institution. Dichotomized time thresholds of length of ruptured membranes before delivery were examined in 2-hour increments using bivariate and multivariable analyses to assess the rates of chorioamnionitis and endomyometritis.

RESULTS: Among the 3841 women meeting inclusion criteria, increased rates of chorioamnionitis and endomyometritis were noted at time thresholds of 12 hours (adjusted odds ratio 2.3 [95% confidence interval, 1.2-4.4]) and 16 hours (adjusted odds ratio 2.5 [95% confidence interval, 1.1-5.6]), respectively.

CONCLUSION: We found that when length of time of ruptured membranes before delivery is examined via dichotomized time thresholds, the risks of chorioamnionitis and endomyometritis are significantly increased at 12 hours and 16 hours, respectively. These time thresholds derived from dichotomized time analyses should be considered during risk-based counseling and labor management in the setting of term premature rupture of membranes.