Cervical insufficiency and short cervix


  • Cervical insufficiency and short cervix can cause problems during pregnancy, including premature birth and miscarriage.

  • Treatment can help you have a healthy pregnancy and stay pregnant longer. 

  • Your provider may want to check your cervix early in pregnancy if you’ve had a premature baby in the past or repeat miscarriages. 

What is the cervix?

The cervix is the opening to the uterus (womb) that sits at the top of the vagina (birth canal). It opens, shortens and gets thinner and softer so your baby can pass through the birth canal during labor and birth. 

In some women, the cervix opens too early during pregnancy or is shorter than normal. These conditions can cause problems during pregnancy.

What is cervical insufficiency?

Cervical insufficiency (also called incompetent cervix) means your cervix opens (dilates) too early during pregnancy, usually without pain or contractions. Contractions are when the muscles of your uterus get tight and then relax. They help push your baby out of your uterus during labor and birth. 

Cervical insufficiency can cause premature birth and miscarriage. Premature birth is when your baby is born too early, before 37 weeks of pregnancy. Miscarriage is when a baby dies in the womb before 20 weeks of pregnancy. 

If your provider thinks you may have cervical insufficiency, she may check you regularly during pregnancy with transvaginal ultrasound starting at 16 to 20 weeks of pregnancy. Transvaginal ultrasound is an ultrasound in the vagina, not on the outside of your belly. An ultrasound is a prenatal test that uses sound waves and a computer screen to show a picture of your baby in the womb.

Your provider also may recommend a cerclage. This is a stitch your provider puts in your cervix to help keep it closed. You can get a cerclage as early as 13 to 14 weeks of pregnancy, and your provider removes the stitch at about 37 weeks of pregnancy. Cerclage may be right for you if you’re pregnant now with just one baby and: 


  • You had a cerclage in a past pregnancy.
  • You’ve had one or more pregnancy losses in the second trimester.
  • You had a spontaneous premature birth before 34 weeks in a past pregnancy with a cervix shorter than 25 millimeters (about 1 inch) before 24 weeks of pregnancy. Spontaneous means that labor began on its own.
  • In this pregnancy, your cervix is opening in the second trimester.

A cerclage is not recommended if you’re pregnant with twins, even if your cervix is shorter than 25 millimeters.

We don’t always know why cervical insufficiency happens. You’re more likely than other women to have it if: 

  • You have defects in your uterus, like if it’s split into two sections. 
  • You’ve had surgery on your cervix.
  • You have a short cervix. The shorter the cervix, the more likely you are to have cervical insufficiency.
  • You’ve had injuries to your uterus that happened during a previous birth.

What is short cervix? 

A short cervix means the length of your cervix (also called cervical length) is shorter than normal. You may find out that you have a short cervix during an ultrasound that you get as part of your regular prenatal care. Prenatal care is medical care you get during pregnancy. 

Checking for a short cervix is not a routine prenatal test. Your provider probably doesn’t check your cervical length unless:


  • She has a reason to think it may be short.
  • You have signs of preterm labor. This is labor that begins too soon, before 37 weeks of pregnancy. 
  • You have risk factors for premature birth, like you had a premature birth in the past or you have a family history of premature birth (premature birth runs in your family). 

If your provider thinks you have a short cervix, she may check you regularly with ultrasound.

If you have a short cervix, you have a 1-in-2 chance (50 percent) of having a premature birth. If you have a short cervix and you’re pregnant with just one baby, your health care provider may recommend these treatments to help you stay pregnant longer:

  • Cerclage
  • Vaginal progesterone. Progesterone is a hormone that helps prepare your body for pregnancy. It may help prevent premature birth only if you have a short cervix and you’re pregnant with just one baby. You insert it in your vagina every day starting before or up to 24 weeks of pregnancy, and you stop taking it just before 37 weeks. 

Many things can affect the length of your cervix, including:

  • Having an overdistended (stretched or enlarged) uterus
  • Problems caused by bleeding during pregnancy or inflammation (irritation) of the uterus
  • Infection
  • Cervical insufficiency

Last reviewed: August, 2015