BACKGROUND Use of quantitative fetal fibronectin (fFN) testing to predict spontaneous preterm birth (sPTB) is gaining attention owing to its absolute measurement of fFN concentration and increased positive predictive value compared with qualitative testing. OBJECTIVE To assess the predictive values of quantitative fFN for sPTB in different predefined thresholds using systematic review and meta-analysis. METHODS Five major databases (PubMed, ScienceDirect, Web of Science, Embase, Cochrane library) were searched for eligible studies. METHODS Observational studies of the diagnostic accuracy of different quantitative fFN thresholds on delivery outcomes were included. METHODS Articles were reviewed independently by two authors and data were extracted. Sensitivity, specificity, diagnostic odds ratio, and summary receiver operating characteristic curves were extracted and calculated. RESULTS Fifteen studies were included. To detect sPTB at less than 34 weeks of gestation, pooled sensitivities for thresholds of 10, 50, 200, and 500 ng/ml were 0.78, 0.56, 0.33, and 0.11, respectively. Pooled specificities were 0.63, 0.84, 0.96, and 0.99, respectively. CONCLUSIONS Based on the results of the meta-analysis, the threshold of 10 ng/ml fFN may be a new choice for the prediction of sPTB. The improved diagnostic accuracy of quantitative testing over qualitative testing can provide additional discriminatory information for clinical practice.