Fibronectin is a glycoprotein that binds amnion and chorion to the decidua of uterus. Normally present in the cervicovaginal secretions before 22 weeks and after 37 weeks of pregnancy. Presence of Fibronectin (>50ng/ml) in between these weeks is suggestive of preterm labor. When the test is negative it reassures that delivery will not occur within next 7 days.