Progesterone belongs to a group of steroid hormones called progestogens. It is mainly secreted by the corpus luteum in the ovary during the second half of the menstrual cycle. It plays an important role in the menstrual cycle and in maintaining the early stages of pregnancy. Other key roles that progesterone plays are:
Maintains the uterine lining and prevents excess tissue buildup.
Inhibits breast tissue overgrowth
Normalizes blood clotting
Improves the action of thyroid hormones
Progesterone is a natural steroid hormone that is found in much higher concentrations in women than in men.