Currently, there is no definitive way to predict preterm labor or premature birth. Many research studies are focusing on this important issue. By identifying which women are at increased risk, health care providers may be able to provide early interventions, treatments, and close monitoring of these pregnancies to prevent preterm delivery or to improve health outcomes.
However, in some situations, health care providers know that a preterm delivery is very likely. Some of these situations are described below.
As a preparation for birth, the cervix (the lower part of the uterus) naturally shortens late in pregnancy. However, in some women, the cervix shortens prematurely, around the fourth or fifth month of pregnancy, increasing the risk for preterm delivery.
In some cases, a health care provider may recommend measuring a pregnant woman’s cervical length, especially if she previously had preterm labor or a preterm birth. Ultrasound scans may be used to measure cervical length and identify women with a shortened cervix.1
The cervix normally remains closed during pregnancy. In some cases, the cervix starts to open early, before a fetus is ready to be born. Health care providers may refer to a cervix that begins to open as an "incompetent" cervix. The process of cervical opening is painless and unnoticeable, without labor contractions or cramping.2
Approximately 5 to 10 out of 1,000 pregnant women are diagnosed as having an incompetent cervix.3
To try to prevent preterm birth, a doctor may place a stitch around the cervix to keep it closed. This procedure is called cervical cerclage (pronounced sair-KLAZH
). NICHD-supported research has found that, in women with a prior preterm birth who have a short cervix, cerclage may improve the likelihood of a full-term delivery.4
- Society for Maternal-Fetal Medicine Publications Committee, with the assistance of Vincenzo Berghella, M.D. (2012). SMFM Clinical Guideline: Progesterone and preterm birth prevention: translating clinical trials data into clinical practice. American Journal of Obstetrics and Gynecology, 206, 376–386. [top]
- Drakeley, A. J., Roberts, D., & Alfirevic, Z. (2003; published online 2010). Cervical stitch (cerclage) for preventing pregnancy loss in women. Cochrane Database of Systematic Reviews, 1. Retrieved May 4, 2012, from, http://summaries.cochrane.org/CD003253/cervical-stitch-cerclage-for-preventing-pregnancy-loss-in-women [top]
- Denney, J. M., Culhane, J. F., & Goldenberg, R. L. (2008, November 5). Prevention of preterm birth. Women's Health, 4, 625–638. Retrieved April 17, 2012, from http://www.medscape.com/viewarticle/582761_10 [top]
- Owen, J., Hankins, G., Iams, J. D., Berghella, V., Sheffield, J. S., Perez-Delboy, A., et al. (2009, October). Multicenter randomized trial of cerclage for preterm birth prevention in high-risk women with shortened midtrimester cervical length. American Journal of Obstetrics and Gynecology, 201(4), 375.e1–375.e8. [top]