Risk factors associated with shortened latency before delivery in outpatients managed for preterm prelabor rupture of membranes

Introduction: Preterm prelabor rupture of membranes (PPROM) occurs in 3% of pregnancies and is the main cause (similar to 30%) of premature delivery. Home care seems to be a safe alternative for the management of patients with PPROM, who have a longer latency than those with PPROM managed with conventional hospitalization. We aimed to identify the risk factors associated with a shortened latency before delivery in women with PPROM managed as outpatients. Material and methods: The design was a retrospective cohort study and the setting was a Monocentric Tertiary centre (Lille University Hospital, France) from 2009 to 2018. All consecutive patients in home care after PPROM at 24-36 weeks were included. For the main outcome measure we calculated the latency ratio for each patient as the ratio of the real latency period to the expected latency period, expressed as a percentage. The risk factors influencing this latency ratio were evaluated. Results: A total of 234 patients were managed at home after PPROM. Mean latency was 35.5 +/- 20.7 days, corresponding to an 80% latency ratio. In 196 (83.8%) patients the length of home care was more than 7 days. A lower latency ratio was significantly associated with oligohydramnios (p < 0.001), gestational age at PPROM (p = 0.006), leukocyte count at PPROM more than 12 x 10(9)/L (p = 0.025), and C-reactive protein concentration more than 5 mg/L at 7 days after PPROM (p = 0.046). Cervical length was not associated with a lower latency ratio. Conclusions: Women with PPROM managed with home care are stable. The main risk factor associated with a reduced latency is oligohydramnios. Outpatients with oligohydramnios should be informed of the probability of a shortened latency period.