Prediction of preterm delivery among women with threatened preterm labor.

Background/aims: 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.

Methods: 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.

Results: 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.

Conclusion: 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.