Incompetent Cervix and Miscarriage Causes

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Cervical insufficiency, formerly called "incompetent cervix," means that a woman’s cervix shortens, weakens, and begins dilating and opening too early in the pregnancy. This 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 outcomes such as severe birth defects or even 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 loop electrocautery excision procedure (LEEP), laser ablation, and cold knife cone excision (CONE). 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 (a medication thought to prevent miscarriage but eventually linked to reproductive issues in future generations). Some research indicates that cervical insufficiency may be more likely in women who have had multiple D&Cs (a surgical procedure used to complete a miscarriage in cases where the uterus fails to empty the contents of a lost pregnancy).


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.


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 or premature delivery). In women at high risk, doctors can monitor the cervix by using vaginal ultrasound, but ultrasound does not always accurately detect cervical changes. Some doctors also routinely screen with fetal fibronectin (FFN) tests to detect potential pre-term delivery.


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 typically without clear signs or symptoms, which is why so few women are aware of this condition until it is too late.

Consider finding a support group (in person or online) 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.

Nearly one-third of pre-term deliveries can be avoided with active management and treatment. 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. Bed rest is no longer recommended; instead, your doctor will advise modified activity.

For women with a history of a prior spontaneous preterm birth between 20 weeks and 36 weeks and 6 days of gestation, the use of 17-α hydroxyprogesterone caproate (a synthetic form of the hormone progestin) has been shown to reduce the risk of recurrent preterm birth by more than 30%.

A Word From Verywell

Even if it's determined that you don't have cervical insufficiency, there are other cervical issues that can cause potential pregnancy complications. These include having other surgical procedures or even a Cesarean section which caused damage to the cervix. Talk to your doctor about any potential concerns you may have. Not only can this help put you on the safest path to a healthy pregnancy and delivery, but it will help to put your mind at ease as well.

5 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Lotgering FK. Clinical aspects of cervical insufficiencyBMC Pregnancy Childbirth. 2007;7 Suppl 1(Suppl 1):S17. doi:10.1186/1471-2393-7-S1-S17

  2. Vink J, Feltovich H. Cervical etiology of spontaneous preterm birthSemin Fetal Neonatal Med. 2016;21(2):106–112. doi:10.1016/j.siny.2015.12.009

  3. Arisoy R, Yayla M. Transvaginal sonographic evaluation of the cervix in asymptomatic singleton pregnancy and management options in short cervixJ Pregnancy. 2012;2012:201628. doi:10.1155/2012/201628

  4. Kersting A, Wagner B. Complicated grief after perinatal lossDialogues Clin Neurosci. 2012;14(2):187–194.

  5. Gupta S, Roman AS. 17-α hydroxyprogesterone caproate for the prevention of preterm birth. Womens Health (Lond). 2012;8(1):21-30. doi:10.2217/whe.11.78

Additional Reading

By Krissi Danielsson
Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage.