Why it's done

Before pregnancy, the cervix is closed, long and firm. During pregnancy, the cervix gradually softens, decreases in length (effaces) and opens (dilates) in preparation for birth. If you have an incompetent or short cervix, however, your cervix might begin to open too soon. As a result, you could experience pregnancy loss or give birth prematurely.

Your health care provider might recommend cervical cerclage during pregnancy to prevent premature birth if you have:

• A history of second trimester pregnancy loss related to painless cervical dilation in the absence of labor or placental abruption (history-indicated cervical cerclage)
• Prior cerclage due to painless cervical dilation in the second trimester
• Painless cervical dilation diagnosed during the second trimester
• A short cervical length (less than 25 millimeters) before 24 weeks of pregnancy, in a singleton pregnancy

Cervical cerclage isn't appropriate for everyone at risk of premature birth. Your health care provider might not recommend a cervical cerclage if you have:

• Active vaginal bleeding
• Active preterm labor
• An intrauterine infection
• Preterm premature rupture of membranes — when the fluid-filled membrane that surrounds and cushions the baby during pregnancy (amniotic sac) leaks or breaks before week 37 of pregnancy
• Twin or higher order pregnancy
• A fetal anomaly incompatible with life
• Prolapsed fetal membranes — a condition in which the amniotic sac protrudes through the opening of the cervix