Understanding Estrogen & Progesterone

Together with progesterone, another female hormone made by the ovaries, estrogen regulates the changes that occur with each monthly period and prepares the uterus for pregnancy. Prior to menopause, more than 90% of the estrogen in a woman's body is made by the ovaries. Other organs (including the adrenal glands, liver, and kidneys) also make small amounts of estrogen. That's why women continue to have low levels of estrogen after menopause. Because fat cells can also make small amounts of estrogen, women who are overweight when they are going through menopause may have fewer problems with hot flashes and osteoporosis (both of which are related to lack of estrogen).

Some of the other important benefits of estrogen become apparent when estrogen levels decline after menopause. For instance, estrogen stimulates skeletal growth and helps maintain healthy bones. It also helps protect the heart and veins by increasing 'good cholesterol' (HDL or high-density lipoprotein) and lowering 'bad cholesterol' (LDL or low-density lipoprotein). Estrogen may also affect a woman’s sexual desire.

Progesterone is the second most important female hormone. Like estrogen, most progesterone is made by the ovaries, with a smaller amount made by the adrenal glands. The job of progesterone is to:

• Stimulate the growth of a cushiony lining in the uterus where the fertilized egg can grow and develop into a baby
• Help the breast make milk
• Generally maintain pregnancy