MGA has antigonadotropic effects in humans at sufficient doses, capable of profoundly suppressing circulating androgen and estrogen concentrations. The antigonadotropic effects of MGA are the result of activation of the PR, which suppresses the secretion of the gonadotropins – peptide hormones responsible for signaling the body to produce not only progesterone but also the androgens and the estrogens – from the pituitary gland as a form of negative feedback inhibition, and hence downregulates the hypothalamic–pituitary–gonadal axis (HPG axis), resulting in decreased levels of the sex hormones and interference with fertility. As such, MGA has functional antiandrogenic and antiestrogenic effects as well as contraceptive effects via its antigonadotropic effects.