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Cervical insufficiency, previously referred to as cervical incompetence, has classically been defined as painless dilation of the cervix in the absence of contractions or bleeding in the second trimester resulting in recurrent pregnancy losses. Painless mid-trimester cervical dilation is an uncommon finding in the general population occurring in less than 1% of pregnancies. Cerclage for the prevention pregnancy loss in cases with both prior preterm births and/or second trimester losses, as well as second trimester cervical dilatation in the index pregnancy, was first reported in the 1950's. Cerclage placement in this setting has been variably referred to as "physical exam-indicated cerclage", "rescue cerclage", and "emergency cerclage". To date, the benefits of cerclage for this indication are not entirely clear.

A recent meta-analysis showed that physical exam-indicated cerclage is associated with a reduction in perinatal mortality and prolongation of pregnancy when compared to no such cerclage.

Recently, several RCTs have shown that cervical pessary could decrease the incidence of PTB in several populations.

Thus, the aim of our trial as noninferiority trial is to evaluate the efficacy of pessary compared to cervical cerclage in prevention of PTB in women in the setting of mid-trimester cervical dilation

Inclusion Criteria:

• Singleton pregnancies
• Cervical dilation between 1 to 5 cm and/or visible membranes by pelvic exam or speculum exam between at 16-23 6/7 weeks gestation

Exclusion Criteria:

• Pessary or cerclage already in situ
• active vaginal bleeding
• Placenta previa/accreta
• Multiple gestations
• Amniotic membranes prolapsed beyond external os into the vagina, unable to visualize cervical tissue
• Ruptured amniotic membranes at the time of diagnosis of dilated cervix
• Cervical dilation more than 5 cm
• Labor (progressing cervical dilation) or painful regular uterine contractions