estrogen /es″trojən/ [Gk, oistros, gadfly, genein, to produce] , one of a group of hormonal steroid compounds that promote the development of female secondary sex characteristics. Human estrogen level is elaborated in the ovaries, adrenal cortices, testes, and fetoplacental unit. During the menstrual cycle, estrogen renders the female genital tract suitable for fertilization, implantation, and nutrition of the early embryo. Pharmaceutic preparations of estrogen are used in oral contraceptives to prevent pregnancy, palliate certain types of postmenopausal breast cancer and prostatic cancer, inhibit lactation, and treat threatened abortion and ovarian disease. Estrogen replacement therapy may be prescribed to relieve the vasomotor symptoms of menopause. Its long-term continued use increases the risk of endometrial carcinoma. Also spelled oestrogen. Formerly called estrin. Kinds include conjugated estrogen, esterified estrogen, estradiol, estriol, estrone.
