distortedcreativity, I don't know much about this subject. But I do know I started my period when I was 9 years old. I was in 5 th grade. It was hit and miss, and not regular but frequent enough that I know that is definitely what it was. My parents didn't know any thing was potentially wrong. They just figured it was time. 30 years later society knows,I hope, that it is not healthy or normal.
Over the course of the years, I have had no harmful side affects. I have 3 beautiful children. I have regular periods, and have had no further issues. I just started early and that is it as far as I know.
I ma not 39 and am dealing with pre-menopausal symptoms. The dr says well you started early then most and you are going threw this to earlier then most. But no concerns. I hope that helps put your mind at ease some.