Oncofetal fibronectin in patients with false labor as a predictor of preterm delivery

Abstract

Our objective was to determine whether fetal fibronectin is a discriminator for preterm labor and early delivery in women who have intact membranes and uterine activity. In our prospective study 28 women between 24 and 34 weeks' gestation with regular, persistent uterine contractions (> 10/hr) and intact membranes were assessed for presence of fetal fibronectin. A Dacron swab was applied to the external os for 10 seconds. The cervix was < or = 1 cm, and all patients were diagnosed as having false labor. The assay was performed by using monoclonal antibody FDC-6 to bind fetal fibronectin. Of the 28 patients with false labor, 14 had a positive fetal fibronectin, and all had preterm labor (specificity and positive predictive value 100%). Of these, nine delivered preterm, yielding a specificity and positive predictive value of 72% and 64%, respectively. Among the 14 women with a negative fetal fibronectin, only four developed preterm labor (sensitivity 78%, negative predictive value 71%). One patient delivered preterm at 34 weeks (sensitivity 90% and negative predictive value 93%). A positive fetal fibronectin in women who have false labor indicates a significant risk for preterm labor and early delivery. A negative fetal fibronectin is a reassuring sign.