L.S.
If the placenta doesn't migrate up the uterus by the time you are about 36 weeks at latest, you will have a c-section. If you try a vaginal delivery with a full on placenta previa you and the baby have a high percentage chance of not living through it. Now. If you are 6-8 weeks, even 12 weeks with a previa, there will be other sonos to see how far the placenta will migrate up the uterus. If it does and is out of the cervical area, you will be fine. If it doesn't, plan on your doc talking to you about a section no later than 38 weeks to make sure your body doens't kick into labor so that the placenta doesn't abrupt (shear off from the uterine wall). Please keep us informed. When found and monitored early on, you two have a high chance of being just fine. Its those who don't know until delivery that have the major problems.
L.
Student Midwife