Progesterone production is regulated by the hypothalamic-pituitary-gonadal axis. The release of Gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the pituitary gland to secrete Luteinizing hormone (LH). In the ovary, LH surge triggers ovulation and the formation of the corpus luteum, which produces progesterone. During pregnancy, the placenta takes over progesterone production.