If you are concerned try popping a small pillow under your hip. I have to sleep on my back now because any assymetrical movement causes huge issues with my pelvis, so my Ob told me to be as elevated as possible to reduce the baby weight on my spine. I do wake in the middle of the night with bad back pain but it s not as bad as my pelvis, so I just move as much as I can and have even pulled out the wheat pillow for it.