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What is the fetal fibronectin (fFN) test?

Diana Meeks
Diana Meeks on behalf of Sigma Nursing
Family Practitioner

The fetal fibronectin (fFN) test measures the levels of fFN in secretions from a pregnant woman's vagina and cervix. fFN is a protein produced during pregnancy. It acts like biological glue, attaching the fetal sac to the uterine lining. fFN normally is present in cervico-vaginal secretions up to 22 weeks of pregnancy and again at the end of the third trimester. fFN usually cannot be detected between 24 and 34 weeks of pregnancy.

Health care providers perform the fFN test on women between 24 and 34 weeks of pregnancy. The presence of fFN during these weeks, along with symptoms of preterm labor, suggests that the "glue" may be disintegrating ahead of schedule and alerts health care providers to a possibility of premature labor and delivery.

The sample of cervico-vaginal secretions is collected during a speculum examination. Results usually are available within 24 hours. The result is either positive (fFN is present) or negative (fFN is not present).

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