Causes of Spotting During Pregnancy. Implantation bleeding is a common cause of spotting early on in pregnancy. Implantation bleeding happens when the fertilized egg attaches to the uterine lining. ... This spotting often occurs before a woman even knows she is pregnant and is often mistaken as a pending period.

-- that is what i found on the web. I'm not supposed to get my period til like Saturday and what im having is small amounts of brown spotting. What should i do? How do i know if its poss preg?