18 weeks pregnant ob said placenta previa but that the placenta was just on the edge what is the chances that it'll grow away? and chances of issues

Your OB should have: Told u that the chances are very high it will go away if it is down there i tell my pts no intercourse until i know it is well away from the cervix, at the very least u should be getting another us at 34 weeks to check placenta and the baby and if your 18 us was not the fetal anatomy scan which is usually done at 20 weeks the u should get another one in 4 weeks.