 [ Symptoms ] what causes bleeding in the first trimester of pregnancy [ Disease ] 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 was not 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