Background: Preterm premature rupture of membranes (PPROM) complicates 1% of all pregnancies and occurs in one third of all preterm deliveries. Midtrimester PPROM is often followed by spontaneous miscarriage and elective termination of ongoing pregnancies is offered in many countries. The aim of this retrospective descriptive cohort study was to investigate the natural history of midtrimester PPROM in a jurisdiction where termination of pregnancy in the absence of maternal compromise is unavailable.

Methods: Cases of midtrimester PPROM diagnosed between 14 and 23 + 6 weeks' gestation during April 2007 to June 2012 were identified following a manual search of all birth registers, pregnancy loss registers, annual reports, ultrasound reports, emergency room registers and neonatal death certificates at Cork University Maternity Hospital - a large (circa 8500 births per annum) tertiary referral maternity hospital in southwest Ireland. Cases where delivery occurred within 24 h of PPROM were excluded.

Results: The prevalence of midtrimester PPROM was 0.1% (42 cases/44,667 births). The mean gestation at PPROM was 18 weeks. The mean gestation at delivery was 20 + 5 weeks, with an average latency period of 13 days. Ten infants were born alive (23%; 10/42). The remainder (77%; 32/42) died in utero or intrapartum. Nine infants were resuscitated. Two infants survived to discharge. The overall mortality rate was 95% (40/42). Five women had clinical chorioamnionitis (12%; 5/42) but 69% demonstrated histological chorioamnionitis. One woman developed sepsis (2.4%; 1/42). Other maternal complications included requirement of intravenous antibiotic treatment (38%; 17/42), retained placenta (21%, 9/42) and post-partum haemorrhage (12%; 5/42).

Conclusions: This study provides useful and contemporary data on midtrimester PPROM. Whilst fetal and neonatal mortality is high, long-term survival is not impossible. The increased risk of maternal morbidity necessitates close surveillance.