Fetal  fibronectin (fFN) is a“glue‐like” protein  that bonds  your developing baby to  your  uterus.Fetal fibronectin is detectable in vaginal secretions in the very beginning of pregnancy,when this bond is first forming, and then again at the end of pregnancy, when your body is getting ready to deliver your baby. fFN is a special protein tha literally holds your baby place in the womb.

After the 35^th week  of pregnancy, it begins to break down  naturally, and is detectable.  If  your body is getting ready to give birth prematurely,fFN may be detected before week 35.From weeks22 to 35 in your pregnancy, there should be very little  fFN detectable.FN can often be detected before other symptoms of preterm labor, such as  contractions  and changes  in cervical length.Doctors may use a combination of signs and symptoms when deciding the best course of action to take in relation to your pregnancy.