[little jeremiah]

You can't fool Mother Nature. This is not good.

[metmom]

I've heard that using the pill as a teen does the same thing to a woman's body as a miscarriage or abortion for the first pregnancy. It can allegedly lead to an increased risk of breast cancer as the breast cells start to differentiate as they do early on in a normal pregnancy but because there is no pregnancy carried to term, those changes are never completed and so all those differentiated cells remain in that state and are more susceptible to mutations that could lead to breast cancer in the future. It does seem a reasonable conclusion.