(HCG)
a hormone, similar to the pituitary gonadotrophin that is produced by the placenta during pregnancy. Large amounts are excreted in the urine, and this is used as the basis for most pregnancy test. The level of HCG in the serum is one of the indicators used in the triple marker test for Down's syndrome. HCG maintains the secretion of progesterone by the corpus luteum of the ovary, the secretion of pituitary gonadotrophins being blocked during pregnancy. HCG is given by injection to treat delayed puberty, undescended testes, premenstrual tension, and (with follicle-stimulating hormone) sterility due to lack of ovulation.
Medical dictionary. 2011.