BackgroundWhile tocolytic therapy can halt the process of delivery, some patients return before the 37th week of pregnancy with recurrence of preterm labor signs.ObjectivesThis study was designed to evaluate the efficacy of progesterone in the prolonging of gestation and reduction of neonatal complications.Material and MethodsIn a clinical trial in 2010, 110 singleton pregnant women admitted at Imam Reza Hospital, Mashhad, Iran, with the diagnosis of preterm labor were divided into three groups: 400 mg/d vaginal progesterone suppositories; 250 mg/w 17-alpha-hydroxyl-progestrone-caproate; and a control group with no additional treatment. After delivery, we assessed the duration between the first phases of labor to the recurrence of preterm labor. The neonatal complications, apgar score, birth weight, need for admission to NICU, and congenital malformations were compared between groups.ResultsThe mean gestational age was 34± 3 weeks in the first, 33.5 ± 3 weeks in the second and 32.5 ± 2 weeks in the control group. The duration of first phase of labor was 31 ± 17 days in the first, 36 ± 14 days in the second and 26 ± 22 days in the control group. The difference between study groups and the control group was significant (P < 0.005). The complications were lower in progesterone-receiving group in comparison to the control group.DiscussionThis study reveals that progesterone can significant reduce the rate of recurrent preterm labor and the several possible neonatal complications among women who had treated with tocolytics to suppress the acute phase.