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Diagnosis of Preterm Labor and Delivery

  • Cynthia M. Johnson, MA
Publication Type:

Condition InDepth

Diagnosis of Preterm Labor and Delivery

The doctor will ask about symptoms and health history. Some things that may be done are:

Pelvic Exam

The pelvic exam is done to see if the cervix has begun to dilate or if it is too thin. A person may be in preterm labor if dilation has started. It is measured in 0 to 10 cm (centimeters). Birth often happens after the cervix has dilated to 10 cm. Thinning of the cervix is called effacement. It is given as a percent. A person who is 50% effaced has a cervix that has thinned to half of its original thickness. When the cervix is fully dilated and effaced, then the head can descend with pushing.


  • American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Obstetrics. Practice Bulletin No. 171: Management of Preterm Labor. Obstet Gynecol. 2016 Oct;128(4):e155-64, reaffirmed 2018.
  • How do health care providers diagnose preterm labor? National Institute of Child Health and Human Development website. Available at: https://www.nichd.nih.gov/health/topics/preterm/conditioninfo/diagnosed.
  • Premature labor. American Pregnancy Association website. Available at: https://americanpregnancy.org/healthy-pregnancy/labor-and-birth/premature-labor.
  • Preterm labor. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/preterm-labor.
  • Preterm labor and birth. The American College of Obstetricians and Gynecologists website. Available at: https://www.acog.org/patient-resources/faqs/labor-delivery-and-postpartum-care/preterm-labor-and-birth.
  • Preterm labor and birth. National Institute of Child Health and Human Development website. Available at: https://www.nichd.nih.gov/health/topics/preterm.


  • Elizabeth Margaret Prusak, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.