I had the same complication the other time for my 2nd pregnancy.
It is call placenta praevia aka low lying placenta. Mine was placenta praevia major meaning my placenta was coverin the opening of my cervix completely so baby definately cannot come out down there. It lasted the whole pregnancy and i ended up with an emer c-sect after admitted hospital for 3x for bleeding.
Hope yours will be corrected before delivery! If not (touch wood), plse do take care cos if starts to bleed, first time just abit, 2nd time like urine flows down yr leg and the 3rd time its like RUNNING TAP WATER! Not kidding! Thats what happened to me.
Anyway, relax yourself and look forward to the best!