Progesterone
Progesterone is a hormone that is primarily produced by the corpus luteum and adrenal glands. Its main function is to prepare the female body for pregnancy and support fetal development. During the menstrual cycle, progesterone levels increase in the second half of the cycle, and a drop in progesterone levels can signal the onset of menstruation. Progesterone is often measured on day 21 of the menstrual cycle to confirm whether ovulation has occurred. While progesterone is commonly associated with female physiology, men also produce progesterone in the adrenal glands and testes, where it plays a role in the production of testosterone.