Incompetent Cervix

During pregnancy, your cervix is closed at the lower end. It thins and opens before childbirth. When it opens too early in a pregnancy, it’s called incompetent cervix (also known as cervical insufficiency). Complications linked to incompetent cervix can include premature birth and miscarriage.


What is incompetent cervix?

Incompetent cervix occurs when your cervix opens, weakens or shortens too early in pregnancy. It’s also known as cervical insufficiency. It can cause problems including miscarriage (loss of the pregnancy) and premature birth (being born before 37 weeks of pregnancy).

If you’re at risk for an incompetent cervix or your cervix shows signs of opening too soon, your pregnancy care provider may recommend preventative treatment to avoid pregnancy complications.


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Why does an incompetent cervix cause problems?

Your cervix is at the lower end of your uterus. It opens to your vagina. Before pregnancy, your cervix is closed and firm. As you near your due date, your cervix softens, shortens (effaces) and opens (dilates) so your baby can be born through your vagina.

With cervical insufficiency, your cervix may soften, open or shorten before the fetus is old enough to be born. This puts the fetus at risk for being born too soon — before their organs are fully developed.

How common is incompetent cervix?

Incompetent cervix occurs in about 1 in 100 pregnancies.

Who is at risk for incompetent cervix?

Anyone can develop an incompetent cervix. However, you may be at higher risk if you have:

  • An irregularly shaped cervix or uterus.
  • Experienced a premature birth or miscarriage in the second trimester of pregnancy.
  • Injured your cervix or uterus during a previous pregnancy or childbirth.
  • Had surgery on your cervix.
  • A genetic disorder like Ehlers-Danlos syndrome which may cause cervical weakness and can lead to cervical insufficiency.

Studies have also shown that people who are Black and people expecting multiples (twins, triplets, etc.) are more likely to develop this condition during pregnancy.


Symptoms and Causes

What are signs of incompetent cervix?

Unlike other signs of premature labor like contractions or your water breaking, cervical insufficiency may not cause noticeable symptoms.

In some people, though, signs of the condition include:

  • Pelvic pressure or pain in your belly.
  • Spotting or changes in your vaginal discharge.

Because there are no symptoms, most pregnancy care providers rely on understanding your health history. This tells them if you may be at risk for an incompetent cervix.

What causes incompetent cervix?

Healthcare experts haven’t identified an exact cause for incompetent cervix. However, they know certain factors can put you at risk. These risk factors include damage to your cervix, prior surgeries to your cervix or being born with an irregularly-shaped cervix or uterus.


What week does incompetent cervix happen in pregnancy?

An incompetent cervix can happen at any time in pregnancy. It’s more common in the second trimester of pregnancy (approximately weeks 14 to 27 of pregnancy).

How does an incompetent cervix cause miscarriage?

A miscarriage is the loss of pregnancy before 20 weeks. Think of your cervix as a door between your uterus (where the fetus grows) and your vagina. This door should remain closed — ideally until your due date. If this door opens too soon, the fetus may be born before their organs, bones and other structures are fully grown. Almost 25% of second trimester miscarriages are due to an incompetent cervix. Cervical insufficiency can also cause pregnancy loss after 20 weeks (stillbirth).

It’s important to note that treatment for incompetent cervix is usually successful.

Can you go full term with an incompetent cervix?

Yes, it’s possible with the right treatment. The goal of treating this condition is to prevent premature labor and keep you pregnant as long as possible so the fetus has a chance to fully develop.

Diagnosis and Tests

How is incompetent cervix diagnosed?

Your pregnancy care provider will ask you questions about your health history and your pregnancy symptoms at prenatal appointments. Be sure to let them know if you’ve had a miscarriage or surgery on your cervix. Your provider may want to monitor your cervix more closely based on those risk factors.

Your provider diagnoses incompetent cervix with a pelvic exam and an imaging test called a transvaginal ultrasound (ultrasound using a wand inserted in the vagina). This test allows your provider to measure the length and opening of your cervix.

Management and Treatment

How is incompetent cervix managed or treated?

The goal of treating incompetent cervix is to help you stay pregnant as long as possible. Because it’s hard to diagnose, knowing the risk factors are extremely important. Your provider will decide which treatment is best for you based on your condition and medical history.

Cervical cerclage

A procedure called a cervical cerclage is one way pregnancy care providers try to prevent premature labor. It involves sewing your cervix shut. Cerclage procedures typically happen at around 12 to 14 weeks of pregnancy. Then, around 37 weeks of pregnancy, your provider removes the stitches so a vaginal delivery is possible.

Your provider may recommend cerclage if:

  • You have a history of miscarriage in the second trimester.
  • You’ve had a cerclage in past pregnancies.

Not everyone can have a cerclage. Your provider will not perform the procedure on you if:

  • You’re pregnant with twins, triplets or more. Research shows no improvement in the risk for preterm delivery if you’re carrying more than one fetus.
  • Your cervix has already dilated 4 centimeters.
  • Your membranes have ruptured (your water has broken).

Progesterone supplements

If you have risk factors for incompetent cervix, your provider may recommend taking progesterone supplements beginning in your second trimester.

Increased monitoring with ultrasound

If you have risk factors for cervical insufficiency, your pregnancy care provider may decide to monitor the length of your cervix using ultrasound up until about 24 weeks of pregnancy. If your provider notes changes to your cervix’s length, they may recommend a cerclage. Cervical cerclage can only happen until about the 24th week of pregnancy.

What complications are associated with incompetent cervix?

Incompetent cervix can cause complications, including miscarriage and premature birth.

In rare cases, treatment for cervical insufficiency (cerclage) may involve complications including:

  • Uterine rupture.
  • Internal bleeding.
  • Laceration (cut or tear) on your cervix.
  • Infection.
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Can incompetent cervix be prevented?

No one can prevent an incompetent cervix. However, you can take steps to promote a healthy pregnancy. These steps include:

  • Attending all of your prenatal appointments.
  • Eating a healthy, well-balanced diet.
  • Gaining a healthy weight during pregnancy.
  • Avoiding substances like alcohol and recreational drugs.
  • Taking a prenatal vitamin.
  • Asking your provider before taking any supplements or medications.

Outlook / Prognosis

What can I expect if I have an incompetent cervix?

Cerclage treatment for incompetent cervix is successful in nearly 90% of cases.

Can I get pregnant again if I had an incompetent cervix?

If you’ve had an incompetent cervix in past pregnancies, you’re at risk for having the condition in future pregnancies. Talk to your pregnancy care provider about the risks and how to plan for a safe and healthy pregnancy.

Living With

When should I call the doctor?

Most pregnancy care providers diagnose incompetent cervix after a second trimester miscarriage or preterm birth. Contact your provider if you experience signs of miscarriage during pregnancy, including bleeding, pelvic pain and contractions.

What questions should I ask my doctor?

If you have incompetent cervix, you may want to ask your provider:

  • How great a risk is incompetent cervix?
  • What signs of complications should I look out for?
  • How will I know if treatment is working?

When can I go back to my regular activities?

Most people with an incompetent cervix don’t need to restrict their activities during their pregnancies. Check with your pregnancy care provider to be sure.

A note from Cleveland Clinic

An incompetent cervix (or cervical insufficiency) is when your cervix shortens, weakens or opens too soon during pregnancy. This can cause miscarriage or premature birth. It’s hard to detect incompetent cervix unless you have a history of miscarriage or other risk factors. Be sure to discuss your complete medical history with your provider as well as any pregnancy symptoms you have. Knowing this information can help your provider determine if you’re at risk for cervical insufficiency. In most cases, this condition is treatable with a procedure called a cerclage.

Medically Reviewed

Last reviewed on 10/13/2022.

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