So first off I gotta say that the human body is amazing with what it can do. But here is my question...

There are 3 types of estrogen in the human body, Estradiol (E1), Progesterone (E3) and I forgot the name of the final one (E3). Now the body can take E1 and use leftovers in your system to make E2 in the liver, but it can not make E3 at all unless you have ovaries. E3 plays a big role in breast development, as a matter of fact the higher levels of E3 during pregnancy are the only reason some women reach the final tanner stage of breast development.

So I'm wondering why is it that most doctors only prescribe Estradiol instead of estradiol and progesterone? Yes there are studies that say that artificial progesterone, and naturally high levels of progesterone, can be carcinogenic to breast tissue, but there are an equal number of studies that say the opposite.

Just a disclaimer I am only asking a question for general knowledge, I am not, I repeat I am NOT attempting to self medicate. I post this disclaimer because when this was asked on another forum, the woman was flamed for attempting to self medicate and never got an answer.

Kariann,

I think (and this is an opinion limited to my own research on the subject) that generally doctors no longer prescribe progesterone because of the risk of complications coupled with the fact that the results achieved are not usually any better (or sometimes just marginally so) than what you can get with estradiol.  As I'm sure you know, prolonged use of any medication with even minimal carcinogenic effects is never a good idea, which is why doctors always prescribe the minimum effective dose of estrogen.  If I had to choose between having a greatly elevated risk of liver problems, blood clots, thyroid tumors, and breast cancer or having a slightly smaller cup size-I'd choose the latter any day.  Most physicians simply don't want to take the risk, and I stand by that decision.

E3 is not progesterone.
Estrogens are E1(estrone), E2(estradiol) and E3(estriol), from those E2 is the most potent one. That is the reason why endos prescribe this one.
Progesterone is very different molecule so it can't bind to estrogen receptors. It binds to different receptors and usual opinion is that it promotes breast growth. I am not sure what results are achieved by adding progesterone because studies regarding this subject are very inconsistent.