목적: To evaluate the effectiveness of quantitative fetal fibronectin (fFN) compared to cervical length between 20+0/7 and 33+6/7 weeks for prediction of spontaneous preterm birth at < 37+0/7 among symptomatic preterm labor women. 방법: A prospective observational study was performed of symptomatic women with singleton gestations from January 2014 to April 2016. Eligible women had their cervicovaginal secretions sampled for fFN and their cervical length had made. Then we investigated the sensitivity, specificity, positive predictive value and negative predictive value for spontaneous preterm birth before 37+0/7 weeks of gestation of fFN and short cervix. 결과: Of the 85 study group, 43(50.6%) had spontaneous preterm birth. Using an fFN cut-off 50ng/mL and below 25 quartile of respective gestational age for cervical length, the sensitivity, specificity, positive predictive value and negative predictive value of quantitative fFN to predict preterm birth were 44.2%, 69.0%, 59.4% and 54.7%, respectively; while those for short cervix were 62.8%, 59.5%, 61.4% and 61.0%, respectively. In both positive cases, the sensitivity, specificity, positive predictive value and negative predictive value were 34.9%, 14.3%, 71.4% and 56.3%, respectively. 결론: In women with symptomatic preterm labor, fFN testing alone could not predict preterm birth better than short cervical length, although specificity of fFN for preterm birth is superior to cervical shortening.