ABSTRACT
This chapter deals with the pregnancy-related proteins with known biological activities. Most of these proteins have been detected by their biological activity or with antisera to functional proteins already known. Part of the pregnancy-related proteins is secreted into the fetal or maternal blood or amniotic fluid, or appears in the maternal urine. Others are mainly found in fetal or placental tissues without secretion. Most of the pregnancy-related proteins originate in the placenta. The others are synthesized by the mother or by the fetus. Human Chorionic Gonadotropin (hCG) is a hormone synthesized by the trophoblast. It was detected in 1927 by S. Aschheim et al in the urine of pregnant women where it appears in significant quantities during the first trimester of pregnancy. HCG is secreted already by preimplantation embryos2 and the placental HCG secretion continues to decrease by the time of labor.
