How an Incompetent Cervix May Lead to a Miscarriage

This condition is often only discovered after it's too late

Obstetrician showing pregnant patient ultrasound on digital tablet
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Cervical insufficiency, also called incompetent cervix, means that a woman’s cervix is weakened and begins dilating and opening too early in the pregnancy, which may lead to miscarriage.

When this premature dilation is not detected in time, cervical insufficiency can cause a pregnancy loss or birth of a preterm infant. The outcome of a preterm delivery depends on when the baby is born, with earlier birth being more likely to result in pregnancy loss.


Cervical insufficiency can result from previous cervical damage, such as having had a difficult birth experience or some types of cervical procedures, such as LEEP, laser ablation and cold knife conization. (A standard cervical biopsy does not cause insufficiency.)

It can also occur in women with congenital uterine malformations, such as bicornuate uterus or unicornuate uterus, and in women whose mothers took DES. Some research indicates that cervical insufficiency may be more likely in women who have had multiple D & C procedures.


Unfortunately, cervical insufficiency usually has no symptoms in the first affected pregnancy. The cervix dilates without the woman necessarily noticing any contractions, and then the waters break and the baby is born – sometimes too early to have a chance at survival. Women may have some spotting or bleeding, but usually, by the time the condition is detected, it is too late to stop the preterm birth.

Diagnosis Methods

Cervical insufficiency is not common and doctors do not routinely screen for the condition during pregnancy, except for women with strong risk factors (such as a known uterine malformation or a previous second-trimester miscarriage). In women at high risk, doctors can monitor the cervix by using vaginal ultrasound, but ultrasound does not always accurately detect cervical changes.


It’s never really easy to cope with any pregnancy loss, but in miscarriages due to cervical insufficiency, your baby may have been born alive before passing away. You may find yourself struggling with the idea that your loss might have been prevented if it had been detected in time.

Resist the urge to blame yourself or to reanalyze your experience to see if there were any missed signs, and remember that cervical insufficiency is rarely discovered in advance for first-time losses. Consider finding a support group to talk to others dealing with cervical insufficiency, or seek the help of a counselor.

Treatment in Subsequent Pregnancies

After having a pregnancy loss or other complication due to cervical insufficiency, there's a definite risk that the problem will happen again in the next pregnancy. For this reason, you should be sure to consult with a high-risk pregnancy specialist or other experienced OB/GYN early in your next pregnancy and ideally before conception.

Your doctor will probably give you special instructions in your next pregnancy. You may need frequent prenatal checkups to monitor your cervix, and you may be advised to avoid strenuous exercise or sexual intercourse.

If your cervix does appear to begin dilating too early in your next pregnancy, your doctor may advise bed rest and may perform a cervical cerclage. Doctors may also use cerclage as a precaution in women considered to have very high risk of pregnancy loss.

Cervical cerclage is a type of surgery in which the doctor places a stitch in the cervix early in pregnancy and removes it when the pregnancy has progressed far enough that the baby should be born.

Researchers have not yet determined good guidelines for which patients may benefit from a cerclage and when cerclage may be effective in preventing pregnancy loss.

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Article Sources

  • Ahn, Jennifer T. and Judith U. Hibbard, "The short cervix in pregnancy: Which therapy reduces preterm birth?" OBG Management Aug 2003. 
  • March of Dimes, "Cervical Insufficiency (Incompetent Cervix) and Cerclage". Health Education Center. June 2006. 
  • Ressel, Genevieve W., "ACOG Releases Bulletin on Managing Cervical Insufficiency." American Family Physician 15 Jan 2004. 
  • University of Illinois Medical Center, "Incompetent Cervix." Oct 2006.