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Fetal Fibronectin as a Short-Term Predictor of Preterm Birth in Symptomatic Patients: A Meta-Analysis

Sanchez-Ramos, Luis MD; Delke, Isaac MD; Zamora, Javier PhD; Kaunitz, Andrew M. MD

doi: 10.1097/AOG.0b013e3181b47217

OBJECTIVE: To appraise critically the diagnostic accuracy of cervicovaginal fetal fibronectin as a short-term predictor of preterm birth in patients with signs and symptoms of preterm labor.

DATA SOURCES: We searched MEDLINE, Current Contents, Index Medicus, EMBASE, the Cochrane Library, and syllabi from scientific meetings, and we performed manual searches of references from textbooks and of known primary and systematic review articles. We also contacted authors, experts on this subject, and the manufacturer.

METHODS OF STUDY SELECTION: We targeted cohort studies reporting data on the diagnostic accuracy of fetal fibronectin for the prediction of preterm birth within 7 days in symptomatic patients before 37 weeks of gestation. Case–control studies were excluded. The total analysis included 32 trials with 5,355 overall participants.

TABULATION, INTEGRATION, AND RESULTS: Two authors independently assessed methodological quality and constructed 2×2 tables for assessment of diagnostic measures. Pooled estimates of sensitivity, specificity, and likelihood ratios were obtained using a bivariate random effects model. Tests for publication bias and meta-regression were performed. Sensitivity analyses were performed for studies using different fetal fibronectin assays. The overall pooled estimates for sensitivity and specificity were 76.1% (95% confidence interval [CI] 69.1–81.9) and 81.9% (95% CI 78.9–84.5), respectively. Likelihood ratios for a positive and negative fetal fibronectin test were 4.20 (95% CI 3.53–4.99) and 0.29 (95% CI 0.22–0.38), respectively. Meta-regression analyses found that test accuracy was affected by prevalence, publication year, and blinding of studies. When subgroup analyses were performed for studies using the same assay, the results were similar.

CONCLUSION: The cervicovaginal fetal fibronectin assay has limited accuracy in predicting preterm birth within 7 days of sampling in symptomatic pregnant women.

The cervicovaginal fetal fibronectin assay has limited accuracy in predicting preterm birth within 7 days of sampling in symptomatic pregnant women.

From the Department of Obstetrics & Gynecology, University of Florida College of Medicine—Jacksonville, Jacksonville, Florida; the Clinical Biostatistics Unit, Ramon y Cajal Hospital, Madrid, Spain; and CIBER Epidemiología y Salud Püblica (CIBERESP), Barcelona, Spain.

Corresponding author: Luis Sanchez-Ramos, MD, 653-1 West 8th Street, Jacksonville, FL 32209; e-mail:

Financial Disclosure The authors did not report any potential conflicts of interest.

© 2009 The American College of Obstetricians and Gynecologists