hi, i had exactly the same thing, i went for my scan (34 weeks) about 2 weeks ago and everything was fine, the placenta was no longer a problem and im having a natural birth,
it is worrying, tho the midwifes played it down alot, but thats because the % of cases that recify them selves is enormous,
try not to worry either way, i was told that even if i had to have a c-section there is no added risk to the baby and just not to worry about it, basically the baby has to come out before the placenta and if its lying low they have to perform a c-section to make sure the baby comes first etc etc m sure they explained this,
but as mine did and most others it will probabilly be ok by 34 weeks
good luck xx