Estrogen is a hormone that produces female physical traits and
helps regulate a woman's menstrual cycle. In women, estrogen is produced in
varying amounts throughout the menstrual cycle, mainly by the ovaries.
When a woman's estrogen levels reach a low enough point, she stops
having monthly menstrual periods (menopause). This can happen as part of
natural aging. Or it can happen when a woman's ovaries have been removed or have been damaged
by chemotherapy or radiation. After menopause, a woman's adrenal gland and the
androgen from fat cells produce low levels of estrogen.
Men have low levels of estrogen in their bodies. Overweight and
obese men and women have higher estrogen levels than those with lower body
fat.