Considering the undesirable side effects of menopause and decreased estrogen secretion, it is not surprising that much research has been devoted to developing an effective estrogen replacement regimen. The History of ERT In the 1920's, most clinicians were aware that menopause was associated with a sharp decline in estrogen secretion by the ovaries. The first research to show that estrogen replacement could alleviate some of the symptoms of menopause was performed in the 1940's. In the 1960's and 1970's, it was discovered that estrogen therapy could reduce the risk of osteoporosis in postmenopausal women. In 1975, it was announced that ERT was associated with an increased risk of endometrial cancer .
Oral administration is the most common.
Three classes of estrogens are used for estrogen replacement therapy in the Unites States. These include ethinyl estradiol and diethylstilbestrol. The most commonly used progestins are medroxyprogesterone acetate and megestrol acetate, given cyclically or continuously. Although ERT is very effective in treating menopausal women, it can have some undesirable and dangerous side effects. For this reason, ERT is not normally prescribed for more than 5 to 7 years.