Fetal Fibronectin

This is a test done to help evaluate a pregnant woman's risk of pre-term delivery. It is generally done when you are 26 to 34 weeks pregnant and are having symptoms of premature labor. A Dacron swab is used to take a sample of cervical or vaginal fluid from the back portion of the vagina or from the area just outside the opening of the cervix.

Fetal fibronectin (fFN) is a glycoprotein that can be used to help predict the short term risk of premature delivery. fFN is produced at the boundary between the amniotic sac and the lining of the mother's uterus. This is called the unteroplacental junction. Fetal fibronectin is largely confined to this junction and thought to help maintain the integrity of the boundary. fFN is normally detectable in cervicovaginal fluid during the first 20 to 24 weeks of pregnancy, and then is detectable again after about 36 weeks.

Finding fFN in cervicovaginal fluids after 36 weeks is not unusual as it is often released by the body as it gets ready for childbirth. The elevated fFN found in vaginal fluids early in pregnancy may simply reflect the normal growth and establishment of tissues at the unteroplacental junction with levels falling when this phase is complete. What is known is that fFN that is detected between 24 and 36 weeks of pregnancy is not normal. Elevated levels reflect a disturbance at the uteroplacental junction and have been associated with an increased risk of pre-term labor and delivery. Knowing whether or not a woman is likely to deliver prematurely helps your caregiver plan a course of action. The fFN test is a relatively non-invasive tool to help the caregiver to distinguish between those who are likely to deliver shortly and those who are not.


  • Inform the person conducting the test if you have a medical condition or are using any medications that cause excessive bleeding.

  • Do not have sexual intercourse for 24 hours before the procedure.


Pregnancy = 50 nanograms/ml

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.


Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.


It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.