The cervix is the narrow lower end of the uterus that goes into the vagina.
- In a normal pregnancy, the cervix stays firm, long, and closed until late in the 3rd trimester.
- In the 3rd trimester, the cervix starts to soften, get shorter, and open up (dilate) as a woman's body prepares for labor.
An insufficient cervix may begin to dilate too early in pregnancy. If there is an insufficient cervix, the following problems are more likely to occur:
- Miscarriage in the 2nd trimester
- Labor begins too early, before 37 weeks
- Bag of waters breaks before 37 weeks
- A premature (early) delivery
What Causes It?
No one knows for sure what causes an insufficient cervix, but these things may increase a woman's risk:
- Being pregnant with more than 1 baby (twins, triplets)
- Having an insufficient cervix in an earlier pregnancy
- Having a torn cervix from an earlier birth
- Having past miscarriages by the 4th month
- Having past late-term abortions
- Having a cervix that did not develop normally
- Having a cone biopsy or loop electrosurgical excision procedure (LEEP) on the cervix in the past due to an abnormal Pap smear
How Do I Know I Have It?
Often, you will not have any signs or symptoms of an insufficient cervix unless you have a problem it might cause. That is how many women first find out about it.
If you have any of the risk factors for insufficient cervix:
- Your health care provider may do an ultrasound to look at your cervix when you are planning a pregnancy, or early in your pregnancy.
- You may have physical exams and ultrasounds more often during your pregnancy.
An insufficient cervix may cause these symptoms in the 2nd trimester:
- Abnormal spotting or bleeding
- Increasing pressure or cramps in the lower abdomen and pelvis
How Is It Treated?
If you have an insufficient cervix, your health care provider will likely suggest bed rest. During bed rest, you will be advised not to have sex. Your health care provider may suggest you have a cerclage. This is a surgery to treat an insufficient cervix. During a cerclage:
- Your cervix will be stitched closed with a strong thread for the whole pregnancy.
- You will be given medicine to prevent a miscarriage that could occur from the surgery.
- Your stitches will be removed near the end of the pregnancy, or sooner if labor begins early.
Cerclages work well for many women.
Sometimes medicines such as progesterone are prescribed instead of a cerclage. These help in some cases.
Talk with your health care provider about your situation and treatment options.
Incompetent cervix; Weak cervix
Owen J, Mancuso M. Cervical cerclage for the prevention of preterm birth. Obstectric and Gynecology Clinics. Philadelphia, PA: Elsevier Saunders; 2012;39:1.
Update Date 11/19/2014
Updated by: Cynthia D. White, MD, Fellow American College of Obstetricians and Gynecologists, Group Health Cooperative, Bellevue, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.