Fetal fibronectin and preterm labor
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 occasionally done when preterm labor symptoms are present. The absence of this protein indicates with 99% certainty that preterm labor will not occur in the next week. However, a positive test result for fetal fibronectin does not dependably predict preterm labor.1
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 labor has not started. A positive test result may show that labor has started, but false-positive results are common. False-positive results can occur if a woman has recently had:
- A pelvic exam. To reduce the risk of a false-positive result, it is important that a fetal fibronectin test be done before a manual pelvic exam.
- Sexual intercourse.
- Uterine contractions.
- Bleeding from the vagina.
The fetal fibronectin test is:
- Somewhat expensive and may not be available in all medical testing centers.
- Not useful for predicting labor in women at risk for preterm labor.
- Helpful only for women with symptoms of preterm labor.
| Author: | Kathe Gallagher, MSW | Last Updated: January 19, 2007 |
| Medical Review: | Joy Melnikow, MD, MPH - Family Medicine Kathleen Romito, MD - Family Medicine William Gilbert, MD - Perinatology | |
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