Vaginal fetal fibronectin as a predictor of spontaneous preterm delivery in triplet gestations

To assess the diagnostic accuracy of vaginal fetal fibronectin (fFN) sampling for predicting preterm birth in asymptomatic women carrying triplet gestations.

An historical cohort of patients carrying triplet gestations between 1998 and 2010 was identified from a single practice by chart review. All patients were screened with fFN testing at 2-3 week intervals from 22 weeks to 32 weeks of gestation. Outcomes evaluated were spontaneous preterm birth prior to 28, 30, and 32 weeks' gestation and delivery within 2 and 3 weeks of testing.

There were 56 pregnancies that met criteria for inclusion. For delivery prior to 30 weeks' gestation, the test had a sensitivity of 75%, a specificity of 85.4%, a positive predictive value of 46.2%, a negative predictive value of 95.3%, positive likelihood ratio of 5.13, and a negative likelihood ratio of 0.29 (p < 0.0001). For delivery within 3 weeks of a single fFN assessment, the test had a sensitivity of 53.3%, a specificity of 95.8%, a positive predictive value of 53.3%, a negative predictive value of 95.8%, positive likelihood ratio of 12.7 and negative likelihood ratio of 0.48 (p < 0.0001).

Fetal fibronectin testing provides moderate to high prediction of spontaneous preterm birth in triplet gestations.