Fetal Fibronectin Test

Fetal fibronectin is a protein that’s believed to help keep the amniotic sac “glued” to the lining of the uterus. The amniotic sac is the fluid-filled membrane that cushions your baby in the uterus.

Fetal fibronectin is often present in vaginal discharge before week 22 of pregnancy. Fetal fibronectin also begins to break down and can be detected in vaginal discharge toward the end of pregnancy.

If your health care provider is concerned about preterm labor, he or she might test a swab of secretions near your cervix for the presence of fetal fibronectin between week 22 and week 34 of pregnancy. A positive fetal fibronectin test is a clue that the “glue” has been disturbed and you’re at increased risk of preterm labor.
Who
Pregnant women with symptoms of or at high risk of preterm labor may take this test.
Pregnant women with no symptoms of or at low risk of preterm labor doesn’t need to take this test.
Test Sample
A swab of secretions near your cervix
Test Preparation
None
Result
Results of the fetal fibronectin test are either positive or negative:
  • Positive. A positive result means that fetal fibronectin is present in your cervical fluid. If you have a positive result between weeks 22 and 34, you’re at increased risk of preterm labor.

    Note that false-positive result may occur. Doctors will follow up with other exams when the test result shows positive.

  • Negative. A negative result means that fetal fibronectin isn’t present in your cervical fluid. This indicates that you aren’t likely to deliver in the next two weeks. In fact, a negative result might be the most powerful benefit of the test — allowing you and your health care provider to relax a bit with the knowledge that a premature birth isn’t imminent.

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