Hi x I had placenta previa also and this was found on my 20 wks scan, by the time i had my 32 wk scan to check the placenta had moved and i has a natural birth.
The placenta would be laying in whats called the lower segment, as the baby grows this lower segment does too, which can move the placenta up and awat from the cervix, mine covered my cervix, and i was so worried but everything was fine by time i had my scan, so try not to worry, just remember you will have your baby in your arms, and any pain you have will be worth it!! x