Prediction of preterm delivery among women with threatened preterm labor

To determine predictive values of fetal fibronectin and phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) in cervicovaginal secretions and ultrasonographic measurement of cervical length for delivery <35 weeks in patients with uterine contractions.

Our study included 51 women between 24 and 35 weeks' gestation with uterine contractions and 90 controls. Cervicovaginal samples were analyzed for presence of fetal fibronectin and phIGFBP-1. Cervical length was measured by transvaginal sonography.

Preterm birth rate was 19.6% (10/51) in the study group. Negative predictive values of fetal fibronectin, phIGFBP-1 and ultrasonographic cervical length <20 mm, and <25 mm for delivery <35 weeks were 91.9, 92.3, 91.1, and 90.5%, respectively. Positive predictive values were 50, 58.3, 100 and 66.7%, respectively. When results of fetal fibronectin/phIGFBP-1 test and ultrasonographic cervical length <25 mm were combined, specificity and positive predictive values of each test for delivery within 7 days increased.

Fetal fibronectin and phIGFBP-1 tests have approximately equivalent ability to predict delivery <35 weeks' gestation. An ultrasonographic cervical length measurement >20 mm or a negative fetal fibronectin/phIGFBP-1 test obtained from patients with uterine contractions at 24-35 weeks' gestation may avoid overdiagnosis.