Cerclage Plus Progesterone vs Progesterone Alone in Twin Short Cervix

Inclusion Criteria: * Maternal age ≥ 18 * Twin pregnancy * Asymptomatic short cervix (CL≤30mm) at routine ultrasound investigation * Gestational age at 16+0- 24+0 weeks Exclusion Criteria: A potential paticipant who meets any of the following criteria will be excluded from participation in this trial: * Women with twin pregnancy in which one or both fetuses are diagnosed with a major structural or congenital abnormality that is likely to influence the composite adverse neonatal outcome. * Women with a monochorionic monoamniotic twin pregnancy * A monochorionic twin pregnancy with twin-to-twin transfusion syndrome before or at the time of inclusion. * Patients have indications for vaginal cerclage: Recurrent late miscarriage (from 14 weeks) or preterm birth occurring two or more times. * Women with dilatation of the cervix diagnosed by ultrasound or physical exam * Women with overt symptoms of preterm labor at the time of measurement of the short cervix (regular contractions, PPROM, recurrent blood loss). * Women with the presence of fever ≥ 38 degrees Celsius. * Women with a placenta previa, vasa previa. * Uterine malformations: unicornuate uterus, bicornuate uterus, uterine septum, fibroid… * Severe maternal conditions (heart failure, chronic kidney disease, systemic lupus erythematosus …)