Fetal Fibronectin Test

Overview

During pregnancy, a uterine infection causes inflammation, which can trigger preterm labor. 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 labor. If the test is negative, you probably aren't having preterm labor. But even if the test is positive, it doesn't mean for sure that you're having preterm labor.

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 labor hasn't started. A positive test result may show that labor has started. But false-positive results are common. They can occur if a woman has recently had:

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

The fetal fibronectin test is:

• Not useful for predicting labor in women at risk for preterm labor.
• Helpful only for women with symptoms of preterm labor.
• Somewhat expensive. And it may not be available in all medical testing centers.