Progesterone

Progesterone is a steroidal hormone that plays a central role in the female reproductive cycle. The sex hormone is produced primarily by the adrenal glands, the placenta, and the corpus luteum of the ovaries. In the absence of oocyte fertilization during ovulation, natural progesterone levels in the blood serum decline, and menstruation begins. However, if the egg is fertilized, progesterone levels will increase to support the pregnancy, maintain the corpus luteum, and promote mammary gland development and milk production.