I had back labour with 2 of my babies. With the first, I remember my midwife checking me and telling me that my baby was posterior (face up). This creates contractions which are more painful with a lot of pain in the back. As soon as she turned my baby, that back pain vanished. It felt SO good. Then I had a few more contractions and decided to hop into a warm bath (l love the warm water during labour).

During my labour in the water, my baby flipped again, so that she was posterior (I could immediately feel the difference in my labour pains) and then she flipped on her own to an anterior position (face down, and the best presenting position for birth).

I remember my sister-in-law applying counter pressure to my lower back during my contractions, and I remember the relief that offered while my baby was posterior.

Here's a good video showing how the use of tennis balls can be very effective at relieving back pain during labour.