Cervical length during pregnancy is sometimes associated with preterm labor — labor that begins before week 37 of pregnancy. If you have a short cervix, you might be at increased risk of preterm labor and premature birth. The earlier premature birth happens, the greater the health risks for your baby.
Before pregnancy, your cervix — the lower part of the uterus that connects to the vagina — is normally closed and rigid. During pregnancy, your cervix will gradually soften, decrease in length (efface) and open (dilate) as your baby grows and you prepare to give birth. If your cervix begins to open too soon, you could give birth prematurely.
Various factors can influence cervical length during pregnancy, including:
- Biological differences between women
- Unknown uterine activity
- A uterus that's stretched too far (overdistended)
- Complications caused by bleeding during pregnancy
- Incompetent cervix — a condition that occurs when weak cervical tissue causes or contributes to premature birth or the loss of an otherwise healthy pregnancy
If you experience signs and symptoms of preterm labor — such as regular or frequent contractions, a constant low, dull backache, vaginal spotting, or pelvic pressure — your health care provider might do a pelvic exam to determine if your cervix has begun to open. He or she might also do an ultrasound to measure your cervical length.
If you're in preterm labor, your health care provider will explain possible treatments and the risks and benefits of trying to stop your labor.
If you're not in active preterm labor but meet certain criteria — you're less than 24 weeks pregnant, you have a history of premature birth and an ultrasound shows that your cervix is opening — your health care provider might suggest cervical cerclage. During this procedure, the cervix is stitched closed with strong sutures.
Limited research also suggests that treatment with a form of the hormone progesterone or placement of a silicone device (pessary) around the cervix might decrease the risk of premature birth in women who have short cervixes.
If you're concerned about your cervical length during pregnancy, consult your health care provider. He or she can answer your questions and help you understand how to promote a healthy pregnancy.
Apr. 25, 2012
- Frequently asked questions. Labor, delivery, and postpartum care FAQ087. Preterm labor. American College of Obstetricians and Gynecologists. http://www.acog.org/publications/faq/faq087.cfm. Accessed Feb. 14, 2012.
- Preterm labor and birth. National Institute of Child Health and Human Development. http://www.nichd.nih.gov/health/topics/Preterm_Labor_and_Birth.cfm. Accessed Feb. 14, 2012.
- Johnson JR, et al. Cervical insufficiency. http://www.uptodate.com/index. Accessed Jan. 31, 2012.
- Lockwood CJ. Overview of preterm labor and delivery. http://www.uptodate.com/index. Accessed Feb. 14, 2012.
- Healthy pregnancy: Labor and birth. The National Women's Health Information Center. http://www.womenshealth.gov/pregnancy/childbirth-beyond/labor-birth.cfm. Accessed Feb. 14, 2012.
- Berghella V. Transvaginal ultrasound assessment of the cervix and prediction of spontaneous preterm birth. http://www.uptodate.com/index. Accessed Feb. 10, 2012.
- Simhan HN, et al. Inhibition of acute preterm labor. http://www.uptodate.com/home/index.html. Accessed Feb. 14, 2012.
- Norwitz ER. Transvaginal cervical cerclage. http://www.uptodate.com/index. Accessed Feb. 14, 2012.
- Hassan SS, et al. Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix; a multicenter, randomized, double-blind, placebo-controlled trial. Ultrasound in Obstetrics & Gynecology. 2011;38:18.
- Romero R, et al. Vaginal progesterone in women with an asymptomatic sonographic short cervix in the midtrimester decreases preterm delivery and neonatal morbidity: A systematic review and metaanalysis of individual patient data. American Journal of Obstetrics and Gynecology. 2012;206:124.e1.
- Goya M, et al. Cervical pessary in pregnant women with a short cervix (PECEP): An open-label randomised controlled trial. The Lancet. In press. Accessed April 20, 2012.
- Caritis SN, et al. Cervical pessary use and preterm birth: How little we know. The Lancet. In press. Accessed April 20, 2012.