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The incidence of multiple gestations has increased over the past years, mostly because of increased use of assisted reproductive technologies. Triplet pregnancies are at increased risk of preterm birth (PTB), which is the primary reason for their increased morbidity and mortality compared to singletons. Multiple gestations, including triplets, account for about 3% of all pregnancies in the US but constitute at least 10% of cases of PTB, over 30% of very low birth weight infants, and nearly 20% of infant mortality.

A short cervical length (CL) on transvaginal ultrasound (TVU) has been shown to be a good predictor of PTB, including in multiple gestations. In singletons with a prior PTB and a short CL <25mm before 24weeks, cerclage is associated with significant decreases in PTB and perinatal morbidity and mortality in the meta-analysis of randomized trials (RCTs). On the contrary, the effect of cerclage in multiple gesttations has been insufficiently studied, with meta-analysis data showing a possible harm from cerclage compared to controls.

The aim of this RCT is to evaluate the efficacy of cervical pessary in prevention of PTB in unselected triplet gestations.

We planned to assess outcomes in subgroup analysis of women with short cervical length (TVU CL <30 mm)

Inclusion Criteria:

• 18-50 years of age
• Triplet pregnancy (limits the participants to female gender)
• Gestational age at randomization between 20(0) and 22(6)

Exclusion Criteria:

• Singleton, twin or higher order than triplets multiple gestation
• Twin twin transfusion syndrome
• Ruptured membranes
• Lethal fetal structural anomaly
• Fetal chromosomal abnormality
• Cerclage in place (or planned placement)
• Vaginal bleeding
• Suspicion of chorioamnionitis
• Ballooning of membranes outside the cervix into the vagina
• Painful regular uterine contractions
• Labor
• Placenta previa