Prediction of spontaneous preterm birth in asymptomatic twin pregnancies with the use of combined fetal fibronectin and cervical length.

OBJECTIVE The purpose of this study was to evaluate combined fetal fibronectin (fFN) test result and cervical length (CL) as predictors of spontaneous preterm birth in asymptomatic twin pregnancies. STUDY DESIGN We examined a retrospective cohort of 155 twin pregnancies with combined fFN and CL testing between 22 and 32 weeks gestation. RESULTS A positive fFN test result at 22-32 weeks or a CL <20 mm increased the risk of spontaneous preterm birth at <37, <34, <32, <30, and <28 weeks' gestation. The combination of a positive fFN test result and CL<20 mm had a significantly higher positive predictive value for delivery at all gestational ages than either positive test alone. On adjusted analysis, a positive fFN test result was a stronger predictor of spontaneous preterm birth than a short CL. CONCLUSION In asymptomatic twin pregnancies, fFN and CL testing between 22 and 32 weeks gestation can identify pregnancies that are at significantly increased risk for preterm birth, including deliveries at <28 weeks' gestation.