VALUE OF FETAL FIBRONECTIN AS A PREDICTOR OF PRETERM DELIVERY FOR A LOW-RISK POPULATION

OBJECTIVE: We examined clinical value of cervical fetal fibronectin de tection by a quantitative enzyme-linked immunosorbent assay as a predi ctor of preterm delivery in a population (n = 111) of middle-class pre gnant women considered to be at low risk for preterm delivery. STUDY D ES[GN: In this prospective study, fetal fibronectin samples from cervi covaginal secretions were obtained biweekly from 24 to 34 weeks' gesta tion. RESULTS: Twenty-two (20%) patients had at least one positive fet al fibronectin test result. Eleven women (10%) were delivered spontane ously at <37 weeks; seven of these had at [east: one positive fetal fi bronectin lest result (positive predictive value = 31.8%, sensitivity = 63.6). An additional three women were delivered prematurely because of other obstetric indications, and all had negative fetal fibronectin test results. The remaining 15 patients with at least one positive fe tal fibronectin test result were delivered at term (greater than or eq ual to 37 weeks). Of the seven women with positive fetal fibronectin r esults who were delivered prematurely, five were delivered within 2 we eks of obtaining a positive result. However, there were no obvious cli nical discriminators between true-positive and false-positive: fetal f ibronectin results. Eighty-nine women tested negative, and 85 of these women were delivered at term (specificity = 82.0%). The negative pred ictive value of fetal fibronectin as a predictor of term delivery in t his low-risk population is 96.6%, with odds ratio = 8.8 (95% confidenc e interval 1.9 to 40.3), relative risk = 6.9 (95% confidence interval 1.8 to 26.6), and Fisher Exact Test p = 0.007. CONCLUSIONS: Although n egative biweekly fetal fibronectin determinations for prediction of pr eterm delivery in this low-risk obstetric population correlate well wi th the absence of preterm delivery, they are of limited clinical value for the prediction of preterm birth.