The aim of this study to compare vaginal progesterone supplementation to cervical cerclage for prevention of preterm labor in women with short cervical length and history of previous midtrimester miscarriage and/or preterm labor.

Women with singleton pregnancy and history of preterm labor and/or midtrimester miscarriage in a previous pregnancy will be selected for serial assessment of the cervical length by transvaginal sonography (TVS) starting from 16 weeks till 24 weeks of gestation. Eligible participants in our study will be those who have cervical length of 15-25 mm at 16-24 weeks of gestation. At 16-24 weeks gestational age, all women participating in the study will be randomly allocated into two groups; progesterone group and cerclage group. For women in the progesterone group, vaginal progesterone suppositories will be given in a dose of 400 mg/day. For women in the cerclage group, McDonald cervical cerclage will be performed.

Inclusion Criteria:

• Women with singleton pregnancy.
• History of preterm labor and/or midtrimester miscarriage in a previous pregnancy.
• Cervical length of 15-25 mm by transvaginal sonography (TVS) at 16-24 weeks of gestation.

Exclusion Criteria:

• Age < 20 or > 35 years.
• Congenital uterine malformation.
• Multifetal pregnancy.
• Known major fetal structural or chromosomal abnormality.
• Known allergy or contraindication (relative or absolute) to progesterone therapy.
• Presence of contraindication to cervical cerclage.
• Medical conditions complicating pregnancy.
• Vaginal bleeding.