A synthetic progestogen structurally related to levonorgestrel, with progesterone hormone receptor agonistic activity, used as a contraceptive and hormone replacement agent. Upon administration, desogestrel binds intracellular progesterone receptors in progesterone responsive tissue and the resultant complex interacts with DNA causing either gene transcription or gene repression. This eventually leads to an inhibition of gonadotropin releasing hormone (GnRH) secretion from the hypothalamus and a subsequent inhibition of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release. This prevents ovulation and alters the cervical mucus.