A variety of hormonal chemical compounds produced by the ovaries, influencing the growth and health of female reproductive organs. They are active in many cells throughout the body by interacting with estrogen receptors. The three main naturally occurring estrogens in women are estradiol, estrone, and estriol. Estrogen levels fall after menopause. Several types of estrogen therapies are available for menopause indications. Also available in some contraceptives, but at much higher doses than those used for menopause treatment. See also Estrogen therapy (ET).