Can implantation bleeding be heavy and countinous for 3 days? or more likely to be period? 31 days since last period

Light bleeding: implantation bleeding is very light in character rather spotting than a bleeding. you are possibly experiencing a delayed menstrual period. if your pregnancy test is positive then my concern is that there may be a miscarriage in progress.

It is more likely: to be a period because usually there isn't any bleeding with implantation. When it does occur - it is usually just a drop or two.