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What is cervical incompetence?

An incompetent cervix, also called cervical insufficiency or an insufficient cervix, is a cervix that dilates too early in a pregnancy, before the baby is ready to be born. In a normal pregnancy, the cervix stays firm, long and closed until late into the third trimester. Pregnant women who have an incompetent/insufficient cervix, have an increased risk of:

  • miscarriage in the second trimester
  • early labor (before 37 weeks gestation)
  • water breaking before 37 weeks
  • premature delivery

If your doctor diagnoses you with an incompetent/insufficient cervix, you may need total bed rest and to abstain from sexual intercourse for the remainder of your pregnancy. Your doctor may also recommend cerclage, a type of surgery to treat an insufficient cervix that involves stitching the cervix closed until you are near your due date. In some women, taking the hormone progesterone may be recommended instead of cerclage surgery.

Stacy Wiegman, PharmD
Pharmacy Specialist

Cervical incompetence is a very unfortunate term for when the cervix does not stay closed during pregnancy, leading to premature labor. It does not occur in the first trimester because the fetus and placenta are too small to put enough pressure on the cervix. Later in pregnancy, however, as the weight of the fetus and placenta grow, if the cervix is "incompetent," it will show up on ultrasound as "coning," where the cervix is losing length and is at risk for opening.

Women who have had cervical surgery (such as a cone biopsy for cervical cancer) are at risk for cervical incompetence because now the cervix is shorter. But it's impossible to tell until the woman is pregnant if the cervix will be a problem. Some women, like me, have multiple cervical surgeries and have no problems with pregnancy.

Cervical incompetence happens when the cervix dilates during the second trimester. Because there are no contractions or pain, you could be totally unaware it is happening. In many cases, the causes are unknown. If you have this condition, the amniotic sac may push partially into the vagina and lead to premature delivery.

In some cases, this process can be diagnosed early enough that a cerclage (or stitch) can be placed to hold the cervix closed and prolong the pregnancy.

A short cervix is defined as a cervical length below the 10th percentile, which is around 25 millimeters. It is important because a short cervix can put pregnant women at risk for premature delivery. It is typically measured during the second trimester.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.