OBJECTIVE: Assess the effectiveness of vaginal progesterone for maintenance tocolysis and preterm labor prevention in singleton gestations and preterm uterine contraction in a sample of Iraqi women. STUDY DESIGN: This is a prospective randomized study included 143 singleton gestation (gestational ages range from 30(0/7) to 34(6/7) weeks at enrollment, intact membrane, and without any contraindication for expectant management. Consenting women wererandomized to receive vaginal progesterone (400mg) daily.The data was collected from women who attend the outpatient clinics in different areas of Baghdad including Hay Aljameaa and AL Noaman teaching hospital from the beginning of 2017 to the end of 2018. RESULTS: Data were collected from143 women (75 assigned to vaginal progesterone, 68 designated to control) with a single gestation,Vaginal progesterone has been correlated with a substantial decrease in preterm birth <35 weeks of gestation (95% confidence interval (0.7552% to 24.8754%);( P = 0.0359); high-quality evidence). In fact, vaginal progesterone reduce the incidence of preterm birth (35- 37 weeks) substantially (95% confidence interval (4.6025% to 35.1764%); (P = 0.0117)and the percentage of Live born delivered before 34 weeks (95% confidence interval (3.4821% to 24.6707%); (P = 0.0081), there is a statistical difference in the birth weight (≤ 1500 gm) (P = 0.0388). There were 1(1.33%) fetal deaths in the vaginal progesterone group and 3 (4.41%) in the control group (confidence interval, -3.4383% to 10.9315%, P = 0.2661 low-quality evidence). CONCLUSION: Maintenance tocolysis with vaginal progesterone suppositories is associated with reduced frequency of uterine contractions and the percentage of preterm birthand improve outcome in perinatalperiodfor singleton pregnancy