Predictors of adverse perinatal outcome in twins delivered at < 37 weeks

Multiple gestations are at increased risk for prematurity as well as perinatal mortality and morbidity. The aim of this study was to identify the independent risk factors for adverse perinatal outcome in a large uniform population of twins delivered preterm. We accessed a cohort of twin gestations for the period 1990-2000 delivered at < 37.0 weeks gestation. Chorionicity was established by ultrasound assessment of the dividing membrane, neonatal gender and histologic examination of the placenta at birth. Adverse perinatal outcome was defined as stillbirth, neonatal death, or major neonatal complications. Statistical analysis used contingency tables, Student's t test, one-way ANOVA and logistic regression, with a two-tailed p < 0.05 considered significant. A total of 356 twin gestations (712 twins) were included in the database, and 183 twins (25.7%) had adverse perinatal outcome. Logistic regression analysis demonstrated that gestational age at delivery (p < 0.001), premature rupture of membranes (PROM) (p = 0.004), birth weight discordance (p = 0.009), and 5-min Apgar scores (p = 0.001) were significant and independent predictors of adverse perinatal outcome, whereas monochorionicity and twin-twin transfusion syndrome were not. Gestational age at delivery and birth weight discordance are the most important independent predictors of perinatal mortality or morbidity among preterm twins.