Overview

Fetal fibronectin is a protein that's believed to help keep the amniotic sac "glued" to the lining of the uterus. The amniotic sac is the fluid-filled membrane that cushions your baby in the uterus.

Fetal fibronectin is often present in vaginal discharge before week 22 of pregnancy. Fetal fibronectin also begins to break down and can be detected in vaginal discharge toward the end of pregnancy.

If your health care provider is concerned about preterm labor, he or she might test a swab of secretions near your cervix for the presence of fetal fibronectin between week 22 and week 34 of pregnancy. A positive fetal fibronectin test is a clue that the "glue" has been disturbed and you're at increased risk of preterm labor.

April 21, 2016
References
  1. Lockwood CJ. Diagnosis of preterm labor and overview of preterm birth. http://www.uptodate.com/home. Accessed Feb. 21, 2016.
  2. Fetal fibronectin. Lab Tests Online. https://labtestsonline.org/understanding/analytes/ffn/tab/sample/. Accessed Feb. 20, 2016.
  3. DeFranco EA, et al. Improving the screening accuracy for preterm labor: Is the combination of fetal fibronectin and cervical length in symptomatic patients a useful predictor of preterm birth? A systematic review. American Journal of Obstetetrics and Gynecology. 2013;208:233.
  4. Van Baaren GJ, et al. Risk factors for preterm delivery: Do they add to fetal fibronectin testing and cervical length measurement in the prediction of preterm delivery in symptomatic women? European Journal of Obstetrics & Gynecology and Reproductive Biology. 2015;192:79.
  5. McLaren JS, et al. Prediction of spontaneous preterm birth using quantitative fetal fibronectin after recent sexual intercourse. American Journal of Obstetetrics and Gynecology. 2015;212:89.
  6. Wick MJ (expert opinion). Mayo Clinic, Rochester, Minn. March 23, 2016.