Risk scoring, fetal fibronectin, and bacterial vaginosis to predict preterm delivery

Objective: To determine the value of markers for predicting spontaneous pre term birth. Methods: One hundred forty asymptomatic gravidas were recruited from 20-24 weeks' gestation. Risk score was assessed, vaginal swabs were analyzed for bacterial vaginosis, and cervical and vaginal swab were tested for fetal fi bronectin FDC-6 X18A4, and CAF. Univariate analysis was used to determine p otential predictors land combinations of predictors) of outcome. Multiple l ogistic regression was done to identify independent predictors of spontaneo us preterm birth. Sensitivity, specificity, positive and negative predictiv e values; and odds and likelihood ratios were calculated for significant pr edictors. Results: Predictors significantly associated with the primary outcome were preterm birth-risk score and vaginal fetal fibronection FDC-6 (logistic reg ression odds ratio [ORI 16.9 [95% confidence interval (CI) 3.1, 92.8]) and 8.0 ([95% CI 1.6, 38.2], respectively), bacterial vaginosis, fetal fibronec tin X18A4, fibronectin CAF, and cervical fetal fibronectin FDC-6 were not a ssociated with spontaneous preterm birth; however, the statistical power to assess these variables was limited. The combination of positive preterm bi rth-risk score and vaginal fetal fibronectin FDC-6 had a sensitivity of 44. 4%, specificity of 97.7%, positive predictive value of 57.1%, negative pred ictive value of 96.2%, and a significant likelihood ratio for a positive te st of 19.4 (95% CI 5.1, 73.8). Conclusion: The combination of preterm birth-risk score and vaginal fetal f ibronectin FDC-6 predicted spontaneous preterm birth. Intervention trials a re required to determine whether a combination of screening tests will redu ce rates of spontaneous preterm birth. (Obstet Gynecol 1999;93:517-22. (C) 1999 by The American College of Obstetricians and Gynecologists.).