with my grade 4 PP i didnt bleed until 37 weeks and it was from going nuts with house work i was in hospital for 3 days went home for a few days then had a c section at 38+2 weeks my PP was totally covering the os up until 36 weeks when it moved slightly and ended up 7mm from the os after the c section the specialist said it was half anterior and half posterior which make the different u/s results make sense she said the placenta started at the front and went under bub and wrapped around the back she said most unusual postion and it turned out bub had her cord around her neck so very lucky we had a c section.
My doctor cant believe i had no bleeding until 37 weeks so i guess everyone is different.