Estrogens refer to an entire class of hormones, some of which occur naturally and many of which do not. This critical distinction is often blurry to both modern medicine and the media as well. Estrogens promote secondary sexual development in women. Estrogens are more dominant in the first two weeks of a woman¹s menstrual cycle and prepare her body to get pregnant. The prominent estrogens in women are estradiol, estrone and estriol. Estradiol is the most potent of these hormones and the one most likely to be prescribed after Premarin. Even estradiol has proven to be problematic because it has been prescribed in isolation or with Provera.