The Preterm Prediction Study: prediction of preterm premature rupture of membranes through clinical findings and ancillary testing. The National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

Our objective was to determine the relative importance of demographic characteristics, clinical risk factors, and ancillary screening tests in the prediction of preterm birth as a result of premature rupture of membranes. A total of 2929 women were evaluated in 10 centers at 23 to 24 weeks' gestation. Demographic and clinical characteristics were ascertained. Cervicovaginal fetal fibronectin and bacterial vaginosis were evaluated. Cervical length was measured by vaginal ultrasonography. Patients were evaluated for spontaneous preterm birth caused by preterm premature rupture of membranes at <37 and <35 weeks' gestation. Multivariate analyses were performed separately for nulliparous women and multiparous women. Premature rupture of membranes at <37 weeks' gestation complicated 4.5% of pregnancies, accounting for 32.6% of preterm births. Univariate analysis revealed low body mass index, pulmonary disease, contractions within 2 weeks, short cervix (