With DD1 I was induced with a drip and she was posterior. Felt like awful period cramps in front but a dull, hard pain in my back, made all the worse by being in bed with monitors on etc.
DD2 was spontaneous but also posterior. The back pain was excruciating, I felt like all my bones were being ground together, I could not find a comfortable position at all. Not pleasant! But quick, so I can't complain