During pregnancy, the
cervix is a closed and sealed tunnel between the
uterus and the vagina. Before or during labor and delivery, the cervix
stretches and flattens (effacement). At 24 weeks of pregnancy, the average
cervix is about 35 mm (1.4 in.) long.footnote 1
A short cervix has a length of less than 25 mm (1 in.). Women with a short cervix may have an increased risk of preterm birth. footnote 2
If this is your first pregnancy or if you have never had a preterm birth, having a shortened cervix may not change the way your doctor treats your
pregnancy. But if you have a very short cervix, 20 mm (0.8 in.) or less, your doctor may offer you medicine to help prevent preterm birth.footnote 2
If you have had a preterm birth, you may already be taking medicine (such as progesterone shots), so your doctor may consider other treatments for a short cervix, such as a cerclage, to prevent preterm birth.footnote 2
If you learn that you are at high risk of preterm birth,
make sure that you know the symptoms of preterm labor and that you know what to
do if you have them.
CitationsCunningham FG, et al., eds. (2010). Preterm birth. In Williams Obstetrics, 23rd ed., pp. 804-831. New York: McGraw-Hill.American College of Obstetricians and Gynecologists (2012). Prediction and prevention of preterm birth. ACOG Practice Bulletin No. 130. Obstetrics and Gynecology, 120(4): 964-973.
ByHealthwise StaffPrimary Medical ReviewerSarah Marshall, MD - Family MedicineAdam Husney, MD - Family MedicineKathleen Romito, MD - Family MedicineSpecialist Medical ReviewerKirtly Jones, MD - Obstetrics and Gynecology
Current as ofMarch 16, 2017
Current as of:
March 16, 2017
Sarah Marshall, MD - Family Medicine & Adam Husney, MD - Family Medicine & Kathleen Romito, MD - Family Medicine & Kirtly Jones, MD - Obstetrics and Gynecology
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Last modified on: 8 September 2017