There are the 3 Bio-Equivalent estrogens:
These three chemicals make up human estrogen. The estrogen that has the most volume in the body is estriol (60-80% of circulating estrogens), followed by estradiol and estrone (10-20% each). Estriol is thought to be the weakest acting hormone, but provides a natural hormonal balance in the body, whereas estradiol and estrone are thought be the stronger estrogens. The female body produces large amounts of estriol during pregnancy and has protective properties against such things as estrogen related cancers. Estradiol is the estrogen that can relieve vaso-motor symptoms the best. Estrone is the primary estrogen found in post-menopausal women. It stores it self in the body fat and has more know cancer properties.
What are the functions of estrogens?
What can Bio-Equivalent estrogens be used for?