Fetal fibronectin as a screening test for premature delivery in multiple pregnancies

Objective: To evaluate fetal fibronectin as a screening test for premature delivery in asymptomatic women with multiple pregnancies. Method: In the mid-second trimester, the concentrations of fetal fibronectin in the cervical and vaginal secretions of 68 patients with multiple gestations were sampled weekly by monoclonal antibody immunoassay in order to predict preterm labor. Results: The results for the prediction of preterm labor differ according to whether we consider a single positive result (fetal fibronectin >50 ng/ml) as predictive of preterm labor or whether we only consider at least two consecutive positive results as predictive of preterm labor. The fetal fibronectin test had a sensitivity for preterm birth before 37 weeks of 90.9% and 86.6%, respectively, with a specificity of 68.5% vs. 78.9% and positive and negative values of 73.1% vs. 76.4% and 88.8% vs. 88.2%, respectively. Similar results were obtained for preterm birth before 34 weeks. Conclusion: In a condition such as multiple pregnancy which is already at risk for premature delivery the possibility of raising the specificity of the test with virtually no decrease in sensitivity guarantees better recognition of patients likely to develop premature labor. This possibility can be achieved simply by considering two positive consecutive samples as predictive of preterm labor.