Neonatal pulmonary hypoplasia and perinatal mortality in patients with midtrimester rupture of amniotic membranes--a critical analysis.

OBJECTIVE: We sought to critically assess the risk factors for neonatal pulmonary hypoplasia and perinatal death in patients with preterm rupture of the amniotic membranes from 15 to 28 weeks' gestation. STUDY DESIGN: This was a prospective cohort study. The study patients had preterm rupture of the amniotic membranes at 15 to 28 weeks' gestation and were without fetal anomalies, multiple gestation, and oligohydramnios before rupture of the membranes. The amniotic fluid volume index was determined at admission and weekly afterward until delivery. RESULTS: The incidence of pulmonary hypoplasia was 12.9% (21/163). The overall perinatal mortality rate was 54% (88/163). Logistic regression analysis revealed the following: (1) Gestational age at rupture of the membranes, the latency period, and either the initial or the average amniotic fluid index have significant influence on the development of pulmonary hypoplasia; (2) gestational age at rupture of the membranes and latency period are significant factors in predicting perinatal death. CONCLUSIONS: In this large population of patients with rupture of membranes at 15 to 28 weeks' gestation, gestational age at rupture of the membranes, latency period, and amniotic fluid index were important independent predictors of neonatal pulmonary hypoplasia. In addition, gestational age at rupture of the membranes and latency period were important independent determinants of perinatal death. Expectant management of patients with preterm rupture of the amniotic membranes during this gestational age interval was associated with improved perinatal survival, even though it may increase the risk of pulmonary hypoplasia.