I had this with my 1st bub (Placenta Previa) but luckily it moved up around 35wks taking me out of the high risk category and allowing me to have a VB instead of a C-section...

it is very common and more common for them to move up in later pregnancy...if it doesn't move there can be some bleeding involved and a c-section is necessary, but your medical practitioner will have more info and a strategy if it doesn't move...

best wishes xxx