ObjectiveTo analyze the use of the measurement of uterine cervix length (MUCL) and the fetal fibronectin (fFN) rapid test as predictors of preterm delivery (PTD) in symptomatic pregnant women assisted at the Santa Casa de Misericórdia de Sobral Maternity Hospital.MethodsThis was a prospective and analytic study involving 53 parturients assisted between September of 2015 and July of 2016; the participants were between 24 and 34 weeks of gestational age (GA) and presented complaints related to preterm labor (PTL) prodromes. Vaginal secretion was collected for fFN testing, and the MUCL was obtained via transvaginal ultrasonography.ResultsA total of 58.49% of the subjects showed MUCL < 25 mm, and 41.51% were positive in the fFN rapid test. A total of 48 patients were followed-up until their delivery date, and 54.17% resulted in PTL. The relative risk (RR) for PTD in patients with MUCL < 25 mm was 1.83 (p= 0.09, 0.99–3.36, 95% confidence interval [CI]), with a mean time before delivery of 2.98 weeks. Based on fFN positive results, the RR was 3.50 (p= 0.002, 1.39–8.79, 95%CI) and the mean time until delivery was 1.94 weeks. The RR was 2.70 (p= 0.002, 1.08–6.72, 95%CI) when both tests were used. The RR of PTD within 48 hours, and 7 and 14 days were, respectively, 1.30 (p= 0.11, 95% CI 1.02–1.67), 1.43 (p= 0.12, 95% CI % 0.99–2.06), and 2.03 (p= 0.008, 95% CI 1.26–3.27), when based on the MUCL, and 1.75 (p= 0.0006, 95% CI 1.20–2.53), 2.88 (p= 0.0001, 95% CI, 1.57–5.31), and 3.57 (p= 0.0002, 95% CI 1.63–7.81) when based on positive fFN results. The RR at 48 hours and 7 and 14 days considering both tests was 1.74 (p= 0.0001, 95% CI 1.14–2.64), 2.22(p = 0.0001, 95% CI 1.22–4.04), and 2.76 (p= 0.0002, 95% CI 1.27–5.96), respectively.ConclusionIn symptomatic pregnant women, we concluded that the MUCL < 25 mm associated with positive fFN rapid test indicate increased the risk for PTD. Further studies with larger sample sizes could contribute in supporting the results presented in the current study.