It's hard to answer the "effect" question since I don't know how things would have turned out had I not started the hormones. I am "osteopenic", small boned and low-weight, so my doctor, nutritionist and chiropractor thought this would be a good idea. I have had no negative side effects; my breasts got a little larger (they were always very small) - that wasn't negative. I like the fact that my Rx is compounded based on MY personal blood test results every six months, rather than a one-size fits all, and also that bioidentical estrogens are just that, and aren't some strange unnatural substance being put into my body because some drug company wants to be able to patent their drug. I am 75, people think I'm maybe 60; I'm sure the hormones have helped.