The objective of the present study is to evaluate the effectiveness of two doses of vaginal progesterone(200mg versus400mg) and placebo in improving gestational age in twin pregnancy and its subsequent impact on perinatal outcome.

The use of progesterone in the prevention of preterm birth(PTB) in both singleton and multiple pregnancies has been extensively investigated. Arguably, the use of progesterone is biologically plausible given that uterine quiescence is maintained throughout pregnancy by progesterone and progesterone receptor-mediated inhibition of inflammation, which causes suppression of the contractile genes. There is no benefit of universal vaginal progesterone to reduce PTB rates in multiple pregnancies. One meta-analysis showed a benefit in adverse perinatal outcome in a subgroup of women with a short cervix ≤25 mm, suggesting it may be useful in this group, but the numbers in the study were small and further research is needed. There appears to be no long-term harm caused to infants exposed to progesterone in utero. So the aim of the present study is to evaluate the effectiveness of two doses of vaginal progesterone(200mg versus400mg) and placebo in improving gestational age in twin pregnancy and its subsequent impact on perinatal outcome

Inclusion Criteria:

• Women pregnant in dichorionic twins.
• Transvaginal sonographic cervical length is <25 mm at 18-22 weeks gestational age.
• No symptoms, signs or other risk factors for preterm labor.

Exclusion Criteria:

• Known allergy or contraindication (relative or absolute) to progesterone therapy.
• Monochorionic twins.
• Known major fetal structural or chromosomal abnormality.
• Intrauterine death of one fetus or death of both fetuses.
• Fetal reduction in the current pregnancy.
• Cervical cerclage in the current pregnancy.
• Medical conditions that may lead to preterm delivery.
• Rupture of membranes.
• Vaginal bleeding.

Women pregnant in dichorionic twins.

a double-blind randomized controlled trial