implantation bleeding can last longer than 12 days. it maybe considered something else after so long but that is what my dr. called it. i am not writing this because i think i know more than what wmd gave as an answer. however as a first time pregnant woman who has experienced light bleeding and cramping intermittently from week 3rd through my current 7th week i believe there is not enough information available about 1st trimester bleeding. i read so many articles like this that my head was swimming. i knew i wasn't having a miscarriage but what i was reading (all from credible sources btw) left me feeling like i was either doomed to miscarry or i would be bed ridden. when i went in for an ultra sound the nurse pointed out a little dark area between the amniotic sac and my uterine wall. she said that is where the blood was coming from. at 7w1d i was still experiencing implantation bleeding- it was still attaching in an area. she said it is common and everything was fine! i saw my little button wiggle and we heard a heart beat! baby measures perfectly. not every story is going to end quite as uncomplicated but i want women to have hope. there are a lot of answers- every pregnancy is different. talk to your dr. and never ever assume the worst. there is hope!
what causes bleeding in the first trimester of pregnancy?