it is possible to be pregnant and THINK you are having your period. It is not really your period though. It is either implantation bleeding or an early miscarriage. A real period is when an egg has not been fertilized so your body expells the old lining of the uterus so a fresh one can be prepared for the next ovulation. I have talked to a few girls who said they had their period the first month or two during pregnancy. This bleeding is due to other reasons.
I have heard of people having their period their entire pregnancy. I don't believe the bleeding is as dark or heavy as a regular period, but I have heard of of them having periods the same time their regular period would be.
EDD with baby #1 for hubby and I September 21st, 2003! It's A BOY!
I just had a baby 3 months ago and experienced spotting every month around the same time in my pregnancy. They say heavier women are more likely to get this but I am about average weight and did. I also got cramps with the bleeding and the first two months spotted straight. I thought I was having a m/c but all was fine.