The study is designed as randomized ,placebo-controlled, clinical trial . All women with dichorionic diamniotic twin pregnancy will be followed up in the antenatal care at the out patient clinic. Randomization of cases will be done by computer method . 130 women with dichorionic diamniotic twin pregnancy and cervical length 10mm to 25mm discovered on transvaginal sonogram between 20w to 24w gestational age will be enrolled in the study and will be distributed in two groups:group P (cases ) and group N (controls) . The randomization allocation will be 1 : 1 (vaginal progesterone capsule : placebo).