That is not a sign of pregnancy. Implantation bleeding has not been scientifically proven.
Think about it...something as small as this period ( . ), or smaller, implanting into your uterus causing bleeding, it's just not going to happen.
Please read this link...
http://www.askmehelpdesk.com/womens-...ert-53865.html
So, please, don't "expect" this as a sign of pregnancy as it is NOT a sign of pregnancy.