Here's a website I just found when I did a search on bio-identical hormones.

Ironically, a friend of mine just got here and she told me about these hormones. I'm taking something that I was told is "natural", but check this website out.

Here's an excerpt:

"In contradistinction, a “natural” substance is a compound directly produced from a plant or animal source. By that definition then, Premarin (made from pregnant mare’s urine) is a “natural compound”. Although it may make sense to eat “naturally” and organically, “natural” does not always mean “safe” or “good”. “Natural” has become more of a sales gimmick than anything.

Better to use the words “botanical” to describe plant-sourced and herbal remedies, and “bioidentical” to describe hormonal therapies utilizing products resembling as close as possible those that the human body (used to) produce. "