OBJECTIVE: To describe latency for patients with preterm premature membrane rupture (PPROM) between 24 0/7 and 31 6/7 weeks’ gestation. STUDY DESIGN: Secondary analysis of data collected prospectively in a multicenter clinical trial of magnesium sulfate for cerebral palsy prevention. Women with PPROM and fewer than 6 contractions per hour at enrollment who were candidates for expectant management (n=1377) were included in this analysis. Length of latency was calculated in days by subtracting the time of delivery from the time of membrane rupture. RESULTS: At each week of gestation, median latency between 24-28 weeks was similar at approximately 9 days, but was significantly shorter with PPROM at 29, 30, and 31 weeks (p<0.001). In addition, the percentage of patients remaining undelivered at 7 days and 14 days was similar for PPROM between 24-28 weeks, but decreased significantly after that. For each gestational age, the proportion of patients remaining pregnant declined in a fashion similar to exponential pattern. CONCLUSION: Median latency after PPROM is similar from 24-28 weeks’ gestation, but shortens with PPROM at and after 29 weeks
