My sister had an issue with placenta when she was pregnant. Her placenta was in a different position. It was in front of the baby, when it's supposed to be in the back.
The issue with this is that during natural birth, the baby should come first and the placenta later. So the baby is not cut off from oxygen and nutrition until he or she is born. If the placenta is in the front, it comes out first, leaving the baby without oxygen. If the baby is not delivered quickly at that time, it could be detrimental.
When doctors realized this, they urged her to have a c-section. But a few weeks before delivery, the placenta somehow moved into the right position and she could go ahead with natural birth. It was amazing how that happened.