<unk>  <unk> , also spelled<unk> , is a steroid, a weak estrogen, and a minor female sex hormone. It is one of three major endogenous estrogens, the others being estradiol and estrone. Levels of<unk>  in women who are not pregnant are almost undetectable. However, during pregnancy,<unk>  is synthesized in very high quantities by the placenta and is the most produced estrogen in the body by far, although circulating levels of<unk>  are similar to those of other estrogens due to a relatively high rate of metabolism and excretion. Relative to estradiol, both<unk>  and estrone have far weaker activity as estrogens. In addition to its role as a natural hormone,<unk>  is used as a medication, for instance in menopausal hormone therapy; for information on<unk>  as a medication, see the<unk>  (medication) article.
Estriol
2-Hydroxyestradiol
Estradiol acetate
Estrogen 
Estrogen
11-Ketoprogesterone
Estradiol 
Estradiol