In reference to baby position:
Anterior : baby spine is outwards, so baby is facing your spine
Prosterior : baby spine is next to your spine, so baby is facing out towards your belly button

When referring to your placenta if it is on the front wall of your uterus ie closest to the outside then it is anterior.
If your placenta is on the back wall so closest to your spine, then it is posterior.


So the problem they have in givingyou a cs is that your placenta is both low lying AND on the front. The incision site for a cs is right dow. Low horizontally across around about where your pubic line is or just below it.
The problem is that cutting through this part could well be right on or dangerously close to where you placenta is attached meaning cutting it will cause a massive haemorrage and medically speaking is very silly

HTH