The secretion of estriol occurs through syncytiotrophoblast through fetal precursors. Majority of the hormone is conjugated which is frequented in maternal circulation while a small portion (around 10%)of it is unconjugated (uE3). The levels of unconjugated estriol are used to determine congenital abnormalities as well as erratic chromosomal behavior and the procedure that is used to determine the levels of 4 pregnancy hormones is known as the triple marker test. Alpha-fetoprotein (AFP) is a protein produced by fetal tissue Human chorionic gonadotropin (hCG) is a hormone produced by the placenta Unconjugated estriol (uE3) is a form of estrogen that is produced by the fetus through metabolism. Inhibin A is a hormone produced by the placenta.
