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

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

  • A history of three second-trimester miscarriages or premature births or two second-trimester miscarriages with no other identifiable causes
  • A short cervix — as shown by ultrasound before week 24 of pregnancy — particularly if you've had a cervical injury, a history of premature birth or multiple miscarriages during your second trimester, or the length of your cervix is rapidly decreasing despite treatment with preventive medications
  • Cervical dilation with a visible amniotic sac before week 24 of pregnancy (emergency or rescue cerclage)

If you experience recurrent pregnancy losses despite treatment with preventive medications or cervical cerclage, your health care provider might recommend cervical cerclage before conception. It's possible, however, that the cerclage might reduce your fertility.

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

  • Vaginal bleeding
  • Preterm labor
  • An intrauterine infection
  • Premature rupture of membranes — when the fluid-filled membrane that surrounds and cushions the baby during pregnancy (amniotic sac) leaks or breaks before labor begins
  • Prolapsed fetal membranes — a condition in which the amniotic sac protrudes through the opening of the cervix
  • A multiple pregnancy
  • A significant risk of miscarriage due to a severe fetal abnormality
Feb. 18, 2012