How do health care providers diagnose preterm labor?

If a woman is concerned that she could be showing signs of preterm labor, she should call her health care provider or go to the hospital to be evaluated. In particular, a woman should call if she has more than six contractions in an hour or if fluid or blood is leaking from the vagina.

Physical Exam

If a woman is experiencing signs of labor, the health care provider may perform a pelvic exam to see if:

  • The membranes have ruptured
  • The cervix is beginning to get thinner (efface)
  • The cervix is beginning to open (dilate)

Any of these situations could mean the woman is in preterm labor.

Providers may also do an ultrasound exam and use a monitor to electronically record contractions and the fetal heart rate.

Fetal Fibronectin (fFN) Test

This test is used to detect whether the protein fetal fibronectin is being produced. fFN is like a biological “glue” between the uterine lining and the membrane that surrounds the fetus.1

Normally fFN is detectable in the pregnant woman's secretions from the vagina and cervix early in the pregnancy (up to 22 weeks, or about 5 months) and again toward the end of the pregnancy (1 to 3 weeks before labor begins). It is usually not present between 24 and 34 weeks of pregnancy (5½ to 8½ months). If fFN is detected during this time, it may be a sign that the woman may be at risk of preterm labor and birth.

In most cases, the fFN test is performed on women who are showing signs of preterm labor. Testing for fFN can help predict which pregnant women showing signs of preterm labor will have a preterm delivery.2 It is typically used for its negative predictive value, meaning that if it is negative, it is unlikely that a woman will deliver within the next 7 days.


  1. Berghella, V., Hayes, E., Visintine, J., & Baxter, J. K. (2008, October 8). Fetal fibronectin testing for reducing the risk of preterm birth. Cochrane Database of Systematic Reviews, (4), CD006843. Retrieved April 18, 2012, from external link
  2. Goldenberg, R., Mercer, B., Meis, P., Copper, R., Das, A., McNellis, D., & the NICHD Maternal Fetal Medicine Units Network. (1996). The Preterm Prediction Study: Fetal fibronectin testing and spontaneous preterm birth. Obstetrics and Gynecology, 87, 643–648.
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