Quantitative Fetal Fibronectin to Predict Prolonged Induction of Labor [ID: 1371638

Abstract

INTRODUCTION: Prolonged induction of labor is problematic for patients and providers alike, but we lack clinical tools to help predict time to delivery. We hypothesize quantitative fetal fibronectin may function as a tool to predict prolonged induction. METHODS: We performed a prospective observational study of low-risk patients undergoing induction of labor at 39 0/7 to 41 0/7 weeks. Prior to induction, fetal fibronectin (fFN) sampling (off-label use) and transvaginal cervix length were completed. Median fFN values were compared to time-to-delivery using 12-, 24-, and 36-hour thresholds. Delivery within these thresholds was modeled using logistic regression after controlling for parity, Bishop score, cervical length, and gestational age. Continuous log time-to-delivery was modeled using linear regression. Arrowhead Regional Medical Center IRB granted approval Protocol #21–29. RESULTS: Of 95 patients enrolled, 35 (37%), 70 (74%), and 80 (84%) patients delivered within 12, 24, and 36 hours. Unadjusted tests for differences in median fFN in these groups were nonsignificant. Cervical length and gestational age were removed from adjusted models because of nonsignificance. Regression models showed a significant relationship between fFN and delivery time within 24 hours, but not within 12 or 36 hours. Each 50 ng/mL increase in fFN was associated with 25% higher odds of delivering within 24 hours (adjusted odds ratio [aOR] 1.25, 95% CI 1.01–1.54, P=.04) with a 3.7% decrease in labor time (53-minute reduction in a 24-hour labor) (aOR 0.963, 95% CI 0.929–0.097, P=.04). CONCLUSION: Our findings suggest fFN maybe a useful tool to identify patients who will deliver within 24 hours of induction initiation.