What is Progesterone?

In a woman's body the majority of progesterone is secreted by the corpus luteum, which forms in the ovary following ovulation.  During the second half of each monthly cycle, from ovulation until menses, progesterone is designed to be the dominant hormone.  Not all women produce sufficient amounts of progesterone during the second half of their cycle.  Prior to menopause, as ovarian function wanes, cycles frequently occur where a woman does not ovulate (known as an anovulatory cycle).  This period leading up to menopause is referred to as "perimenopause."  Anovulatory cycles that begin in perimenopause can lead to hormone changes that may result in hot flashes, changes in bleeding patterns, PMS-type symptoms, as well as many other menopausal symptoms.  While progesterone levels fall close to zero due to anovulatory cycles at menopause, estrogen levels may only decline to about 40 - 60% of pre-menopausal levels.  Progesterone has a number of important roles relative to menopause.  It is the natural balancer to estrogen, as well as being necessary for optimum estrogen utilization.  Research over the years has also revealed other vital roles of progesterone on the heart, blood vessels, nerves and brain.  Many women find that supplementing with progesterone allows them to achieve a balance once again.