IRCT201603109568N15 IRCT 2016-03-22 Maternal, Fetal and Neonatal Research Center, Tehran University of Medical Sciences Vaginal progesterone plus cervical pessary for preventing preterm birth The effectiveness of the combined treatment with vaginal progesterone plus cervical pessary compared to vaginal progesterone monotherapy for the prevention of preterm birth: a randomized clinical trial. 2014-08-01 anticipated 144 Complete https://irct.ir/trial/10140 interventional Randomization: Randomized, Blinding: Not blinded, Placebo: Not used, Assignment: Parallel, Purpose: Prevention. N/A Preterm delivery. Intervention 1: Intervention Group: Cervical pessary inserted by an obstetrician, between 18-20 weeks of gestation, in an outpatient setting.A vaginal speculum examination was done to determine the appropriate size. The site with the smallest diameter was placed upwards to surround the cervix. The patients were asked to report any vaginal or pelvic discomfort. The pessary was removed by a simple vaginal examination in the 37th week of gestation, or earlier if the patient presented with rupture of membranes, vaginal bleeding, or painful uterine contractions despite tocolytics. These patients received 400 mg of vaginal progesterone once daily before going to bed until 37th week of gestation. Intervention 2: Control Group: Patients received 400 mg of vaginal progesterone once daily before going to bed until 37th week of gestation.