Predicting Baby's Arrival: The Fetal Fibronectin Test

pregnant woman being monitored at the hospital

Are you wondering if your baby might arrive too early? There’s a way to find out: Ask your doctor if you’re a candidate for the “fetal fibronectin test.” While the name of this test seems scary, it's typically a painless diagnostic test that offers valuable answers and peace of mind.

What does "fetal fibronectin" mean? Simply put, fetal fibronectin is a protein made by fetal cells, and it’s the biological "glue" that holds the fetus’ sac to the uterine lining. If preterm labor is about to occur, the fibronectin will leak into the vagina.

About the Diagnostic Test

The fetal fibronectin test identifies this leakage. The simple test is performed easily in the doctor’s office. A tiny specimen is collected with a vaginal swab and then is sent to a lab for testing. Patients usually can get the results in a few days or sooner.

pregnant woman at the hospital

Understanding Test Results

If the test result is positive, it may not really be a conclusive result. It could mean that labor is imminent, or it can mean that you might not give birth for several weeks.

There is also a chance that a “false positive” result may occur, if the test is done after having had intercourse or following a digital exam of the cervix. So, it’s essential that the swab sample is obtained before either of these circumstances occur.

When the test yields a “true positive” result, your ob-gyn will work with you to address the issues of premature birth. For example, your doctor could prescribe medication to help improve your infant’s lung capacity and development.

On the other hand, a negative test means your pregnancy will probably last for a minimum of one more week or longer. There is a greater than 95 percent probability of not delivering for the following two weeks.

Facts on Preterm Births

Did you know that every year, one of every nine babies is born before reaching full term? (The fetal fibronectin test is prescribed between 22 and 35 weeks gestation.)

The good news is that, thanks to improved awareness and medical advances, preterm births (prior to 37 weeks) have dropped in recent years. In the United States, this rate decreased each year from 2007 – 2011.

newborn being measured after birth

Preterm Labor Precautions

If the fetal fibronectin test shows that you’re at risk for preterm birth, there are precautions to take:

  • Work closely with your ob-gyn.
    Follow your doctor’s orders. He or she may put you on full bed rest and medication.

  • Find out all your risks.
    Figure out if you have any of the following additional risk factors: diabetes, uterine infection, older age at pregnancy, smoking, and drug use? Your doctor can offer suggestions, such as adjusting your diet and exercise regimen, or testing for and treating an infection of the uterus. (Studies indicate that uterine infections that start in the lower genital area may cause up to 50 percent of preterm births.)

  • Ask about medications.
    If you experienced a previous preterm delivery, ask whether medications could help. For example, a recent study at Wake Forest University Baptist Medical Center found that a hormone similar to progesterone lowered the incidence of preterm birth by 34 percent in women who had a preterm birth previously.

  • Know the signs of preterm labor.
    If preterm labor has begun, there are ways the delivery can be delayed for up to a week using drugs that subdue contractions. Corticosteroids can then be given to help improve the infant’s lung development.

  • Be diligent about prenatal care.
    Visit your ob-gyn regularly—ask about taking prenatal vitamins that include folic acid. Research shows that folic acid not only reduces the risk of high blood pressure, but it can also lower the chances of the placenta separating from the uterine wall. (Both of these health conditions result in 20 percent of early labor and delivery cases!)