What causes the production of progesterone?

Progesterone is primarily produced by the corpus luteum, a temporary endocrine structure that forms in the ovary after ovulation. The corpus luteum secretes progesterone to prepare the uterus for implantation of a fertilized egg and to maintain a healthy pregnancy. If fertilization does not occur, the corpus luteum degenerates, leading to a decrease in progesterone levels and the start of menstruation. Additionally, the placenta also produces progesterone during pregnancy to support the growth and development of the fetus.