pink,
we did lots of tests & scans, placenta is low but then it's normal at this stage, will move up when womb grows.
the closest explanation that makes sense is that the bleeding seem to come from the placenta detaching from the womb(prob due to the placenta attaching itself to previous scar tissue in the womb).
another explanation is tat the womb is full of blood vessels so when the placenta attaches itself and breaks some of the bigger blood vessels, it results in bleeding, some blood is reasborbed, some is discharged out of the body.
either scenario, the doctors are limited to what they can do.