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. If this connection is disrupted, fetal fibronectin can be released into secretions near your cervix. The connection can be disrupted by an infection, inflammation, the separation of the placenta from the wall of the uterus, uterine contractions or shortening of the cervix.

If your health care provider is concerned about preterm labor, he or she might test a swab of these secretions 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 premature birth within seven days.

However, keep in mind that research hasn't shown this test to improve outcomes immediately before and after childbirth.