What is being tested?
Fetal fibronectin (fFN) is a glycoprotein that can be used to help predict the short term risk of premature delivery. fFN is produced at the boundary between the amnionic sac (which surrounds the baby) and the lining of the mother’s uterus (the decidua) in an area called the uteroplacental (or choriodecidual) junction. Fetal fibronectin is largely confined to this junction and is thought to help maintain the integrity of the boundary. fFN is normally detectable in cervicovaginal fluid during early pregnancy, and in a normal pregnancy it is no longer detectable after 24 weeks. However, it reappears and is again detectable after about 36 weeks.

According to the American College of Obstetricians and Gynecologists (ACOG), a normal pregnancy is 40 weeks with a woman going into labor between 37 and 42 weeks. Finding fFN in cervicovaginal fluids after 36 weeks is not unusual as it is often released by the body as it gets ready for childbirth. The elevated fFN found in vaginal fluids early in pregnancy may simply reflect the normal growth and establishment of tissues at the uteroplacental junction with levels falling when this phase is complete. What is known is that fFN should not be detectible between 22 and 36 weeks of pregnancy. Elevated levels during this period reflect a disturbance at the uteroplacental junction and have been associated with an increased risk of preterm labor and delivery.

How is the sample collected for testing?
A Dacron swab is used to take a sample of cervical or vaginal fluid from the posterior portion of the vagina or from the area just outside the opening of the cervix.