Topic Overview

During pregnancy, a uterine infection causes inflammation, which can trigger preterm labour. This inflammation can also stimulate the amnion cells to produce fetal fibronectin, a protein.

Fetal fibronectin testing is sometimes done when preterm labour symptoms are present. When the fetal fibronectin test is negative, it is unlikely that you are having preterm labour. But even if the test is positive, it does not mean for sure that you are having preterm labour.

For fetal fibronectin testing, 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 and the swab is sent to the laboratory for testing.

A negative test result is quite accurate and shows that labour has not started. A positive test result may show that labour has started, but false-positive results are common. False-positive results can occur if a woman has recently had:

• A pelvic examination. To reduce the risk of a false-positive result, it is important that a fetal fibronectin test be done before a manual pelvic examination.
• Sexual intercourse.
• Uterine contractions.
• Bleeding from the vagina.

The fetal fibronectin test is:

• May not be available in all medical testing centres.
• Not useful for predicting labour in women at risk for preterm labour.
• Helpful only for women with symptoms of preterm labour.