human chorionic gonadotropin

human chorionic gonadotropin A hormone that is made by chorionic cells in the fetal part of the placenta. Abbreviated hCG. hCG is directed at and stimulates the gonads. hCG becomes detectable within days of fertilization, and it forms the foundation of most common pregnancy tests. The level of hCG in maternal serum is also one component in the double and triple screens used during pregnancy to assign risks of Down syndrome and other fetal disorders. See also gonadotropin.