HUMAN CHORIONIC GONADOTROPIN (HCG)

A human hormone made by chorionic cells (in the fetal part of the placenta), hCG is directed at the gonads and stimulates them. hCG becomes detectable (by immunologic means) within days of fertilization and forms the foundation of the common pregnancy tests. The level of hCG in maternal serum also enters as one component in the "double" and the "triple" screens used during pregnancy to assign risks of Down syndrome and other fetal disorders.