Background: Preterm labor is a major cause of neonatal complications. Some researchers have demonstrated that increased serum ferritin level and cervicovaginal ferritin concentrations is associated with preterm labor. Objective: The aim of the current work was to detect the role of serum and cervicovaginal ferritin concentrations in mid gestation in predicting preterm labor in patients with no well-known risk factors for preterm delivery. Patients and methods: This prospective cohort observational study included a total of 100 pregnant women with singleton pregnancies between 20 and 24 gestational weeks, attending at the Department of Obstetrics and Gynecology, Menoufia University Hospital between March 2017 to March 2019. Cases were distributed between 2 groups; Group 1 delivered full-term and group 2 delivered preterm. Cervicovaginal and serum ferritin was measured for them. All cases were followed up till delivery. Results: There is a strong relation between spontaneous preterm delivery and increased levels of serum and cervicovaginal ferritin when measured at gestational age 20–24 weeks. Serum ferritin level ≥110.5 ng/mL gave sensitivity 86.7% and specificity 94.1% in preterm delivery prediction. Cervicovaginal ferritin level ≥25.5 ng/mL gave sensitivity 86.7 % and specificity 64.7% in preterm delivery prediction. Conclusion: It could be concluded that increased serum and cervicovaginal ferritin concentrations in mid gestation are dependable markers for predicting preterm delivery