What is an incompetent cervix, or cervical insufficiency?

If you have cervical insufficiency (sometimes called incompetent cervix), it means that your cervix has started to efface (grow shorter) and dilate (open up) too soon. This can cause you to give birth too early, typically between 16 and 24 weeks. Cervical insufficiency can result in miscarriage or preterm delivery.

The cervix is the narrow, tubular lower end of the uterus that extends into the vagina.

When you're not pregnant, the cervix (also called the cervical canal) remains open a tiny bit to allow sperm to enter the uterus and menstrual blood to flow out. Once you become pregnant, secretions fill the canal and form a protective barrier called the mucus plug.

During a normal pregnancy, the cervix remains firm, long, and closed until late in the third trimester. At that point it usually starts to soften, efface, and dilate as your body prepares for labor.

What causes an incompetent cervix?

You're more likely to experience cervical insufficiency if:

  • You've had a procedure such as a cone biopsy or LEEP done on your cervix.
  • You've had one or more second-trimester miscarriages with no known cause.
  • You've had cervical insufficiency in a prior pregnancy.
  • You've had one or more spontaneous preterm deliveries.
  • You have a uterine abnormality (such as a bicornate uterus).
  • You have a congenital disorder affecting your connective tissue, such as Ehlers-Danlos syndrome.
  • You're African American. We don't know why, but Black women seem to be at higher risk of cervical insufficiency.
  • Your mother took the drug DES (diethylstilbestrol) while she was pregnant with you. Caregivers used to prescribe this drug to prevent miscarriage, but it was taken off the market in the United States in 1971, when studies showed that it was ineffective and caused reproductive tract abnormalities in developing babies. However, DES remained available in other countries, so if your mother lived in another country when she was pregnant with you, ask her whether she took the drug.

What are the symptoms of an incompetent cervix?

You may have no symptoms of cervical insufficiency. Or you may have mild symptoms beginning between 14 and 20 weeks such as:

There is still no good way to screen for cervical insufficiency, but if you're at risk for this condition, your practitioner may order regular transvaginal ultrasounds beginning at 16 weeks to measure the length of your cervix and check for signs of early effacement (shortening).

This screening is usually done every two weeks until you're 23 weeks along. If your practitioner finds significant changes, such as a cervix shorter than 25 millimeters (mm), you're at a much higher risk for preterm birth and may benefit from treatment.

How is cervical insufficiency treated?

Incompetent cervix treatments include:


If an ultrasound shows your cervix is shorter than 25 mm, you're less than 24 weeks pregnant, you're carrying a single baby, and you have other risk factors for cervical insufficiency, such as a prior preterm birth, your practitioner may recommend a cerclage to reduce your chances of preterm delivery.

Cerclage is a procedure in which a band of strong thread is stitched around your cervix to reinforce it and help hold it closed. It's usually performed as an outpatient procedure using spinal anesthesia. You'll then be told to relax for a few days, during which you may have light bleeding or cramping. You'll need to stop having sex for a while or possibly for the rest of your pregnancy.

A cerclage may also be helpful for women whose cervix is found to have opened one or more centimeters before 24 weeks when examined manually or by speculum.

Other women who seem to benefit from cerclage include those who've had multiple unexplained second-trimester losses or preterm births. If you're in this group, you're likely to get a cerclage at 12 to 14 weeks, before your cervix starts to change.

Your practitioner may continue to check your cervix for signs of changes until the stitches come out, usually at 36 to 37 weeks. Once you reach that point, you can relax and wait for labor to begin.

Some women are candidates for a transabdominal cerclage (TAC). Unlike other cerclages, which are placed through the vagina and leave no scar on the body, transabdominal cerclage requires an abdominal operation.

A TAC can be placed in between pregnancies, or early in the first trimester, before 12 weeks. It's a major operation, usually requiring a large incision in the abdomen, similar to a c-section, and an overnight hospital stay. If you have a TAC before you're pregnant, you may be able to have it done by laparoscopy, or robotic surgery, allowing a shorter recovery.

If you have a TAC, you have to deliver by c-section. (The TAC stays in permanently, so the baby cannot be delivered vaginally.) The good news is that more than 80 percent of women who receive a TAC deliver at 35 weeks or later.


Women with a prior spontaneous preterm birth may also be given extra progesterone to reduce the risk of a recurrence. Most practitioners recommend weekly progesterone shots starting at 16 weeks, continuing until 36 weeks. An alternative is a daily dose of progesterone that you can insert vaginally.


If you're experiencing signs of premature labor and an ultrasound shows that your cervix is short and your baby has a chance of survival (usually after 22 weeks), your practitioner may give you steroids. Combined with other medications, steroids can stop preterm labor and help your baby's lungs develop more quickly.

Will I need to be on bedrest?

Some caregivers used to prescribe bedrest in addition to – or instead of – cerclage. But there's no evidence that staying in bed prevents preterm labor or birth, and it may actually have negative effects. Instead, you may be told to reduce your level of activity, refrain from exercise and intercourse, and take frequent breaks to get off your feet.

If I have a cerclage for one pregnancy, will I need one for the next pregnancy?

Not necessarily. Your healthcare provider will want to monitor your cervix with transvaginal ultrasounds, though, to make sure you don't need a cerclage.

If I have a TAC, will I be able to get pregnant again?

Yes, you can still conceive normally, and a TAC is likely to hold during later pregnancies

Join our Cervical Incompetence Support Group.

Join our Cervical Cerclage Support Group.