My first was born posterior and as Clover said, there was a fair bit of back pain. To be honest, with it being my first, I didn't realize that the pain I was feeling wasn't what I should be feeling if bub was the right way round. It was a long delivery, and I was pushing for quite a while, but I birthed her with no drugs and no help so it can be done. I found leaning on the fit ball helped in the earlier stages, and then as it progressed, I was on all fours or leaning over the bed.