Fetal Fibronectin

Reviewed by Traci C. Johnson, MD on December 15, 2020

Who Gets the Test?

The fetal fibronectin test isn't necessary for all pregnant women. Your doctor may suggest it if you're at risk of going into labor early. You may be at higher risk because you're bleeding (not usually because of the actually bleeding but because preterm labor is suspected. It cannot be done if blood is present), have a health problem, have early contractions, or delivered a baby early in the past.

What the Test Does

Fibronectin is a protein that connects the amniotic sac to your uterus -- almost like glue. As the sac begins to separate before birth, your body releases the excess fibronectin.

The test checks the level of fibronectin in your cervix. High levels can mean that you may go into labor early.

How the Test Is Done

The test is simple and safe. Your doctor will take a quick swab from near your cervix. It may be uncomfortable, but it will be quick. Don't have intercourse for 24 hours before the test -- it could cause a false positive result.

What to Know About Test Results

You should hear the results within 24 hours. Low levels of fetal fibronectin rule out the possibility of labor within the next two weeks.

High levels don't necessarily mean that you are going into labor. They just indicate you're at higher risk. Your doctor may want to do more tests, such as ultrasounds. You may need drugs to slow down labor. Your baby may need medication to strengthen the lungs.

How Often the Test Is Done During Pregnancy

It depends on your situation. Talk to your doctor.

Tests Similar to This One

Cervical length measurement

Show Sources


UpToDate: "Fetal Fibronectin for prediction of preterm labor and delivery."

Society for Maternal Fetal Medicine: "Maternal-Fetal Medicine."

American Congress of Obstetricians and Gynecologists: "Preterm Labor."

© 2020 WebMD, LLC. All rights reserved. View privacy policy and trust info