FETAL FIBRONECTIN - A NEW TOOL FOR THE PREDICTION OF SUCCESSFUL INDUCTION OF LABOR

OBJECTIVE: The Bishop score is the only available tool for predicting successful labor induction. Vaginal fetal fibronectin has been shown t o predict which patients will enter labor spontaneously, usually withi n 2 weeks. This study was designed to determine whether fetal fibronec tin can also predict the success of labor induction. STUDY DESIGN: Ter m patients undergoing labor induction had a single swab from the vagin a tested for fetal fibronectin before initiation of cervical ripening or oxytocin. The swab was tested with a blinded qualitative immunoassa y for fetal fibronectin (positive greater than or equal to 50 ng/ml). RESULTS: Of the overall 160 subjects, 108 had a positive and 52 had a negative fetal fibronectin result. Patients with a positive result had a lower cesarean section rate (15% vs 27%, p = 0.05) and shorter inte rvals to delivery, including first dose of prostaglandin to delivery i nterval (21.3 vs 35.8 hours, p = 0.0001) and first stage of labor (14. 8 vs 21.2 hours, p = 0.0009). These differences remain similar even in nulliparous women with Bishop scores less than or equal to 5, with pa tients with positive results having statistically shorter intervals to delivery and similar differences in cesarean section rates (22% vs 35 %), although this difference was not significant. In this subgroup mor e than half the patients in the negative results group (11/20) were un delivered after 24 hours and were judged to require a second dose of p rostaglandin compared with only 2 of 53 in the group with positive res ults (p = 0.000001). By stepwise logistic regression analysis the pred ictive ability of a positive result for fetal fibronectin was found to be independent of the Bishop score. CONCLUSIONS: Vaginal fetal fibron ectin appears to be an efficacious new test that independently predict s which patients will have shorter and easier inductions of labor and lower cesarean section rates, even nulliparous patients with low Bisho p scores. This test has the potential for clinical utility and cost re duction.