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Fetal Fibronectin Test


During pregnancy, a uterine infection causes inflammation, which can trigger preterm labour. This inflammation can also stimulate the amnion cells to produce fetal fibronectin, a protein.

Fetal fibronectin testing is sometimes done when someone has symptoms of preterm labour. If the test is negative, you probably aren't having preterm labour. But even if the test is positive, it doesn't mean for sure that you're having preterm labour.

For this test, a sample of fluid is collected from the vagina or the opening to the uterus (cervix). First, a speculum is used to spread the walls of the vagina to view the cervix. Next, a sterile swab is used to absorb fluid from the cervix or vagina. The speculum is removed. Then the swab is sent to the lab for testing.

A negative test result is quite accurate. It shows that labour hasn't started. A positive test result may show that labour has started. But false-positive results are common. They can occur if a woman has recently had:

  • A pelvic examination. To reduce the risk of a false-positive result, it's important that this test be done before a manual pelvic examination.
  • Sexual intercourse.
  • Uterine contractions.
  • Bleeding from the vagina.

The fetal fibronectin test is:

  • Not useful for predicting labour in women at risk for preterm labour.
  • Helpful only for women with symptoms of preterm labour.
  • Not available in all medical testing centres.


Current as of: November 9, 2022

Author: Healthwise Staff
Medical Review:
Sarah Marshall MD - Family Medicine
Adam Husney MD - Family Medicine
Kathleen Romito MD - Family Medicine
Kirtly Jones MD - Obstetrics and Gynecology