Hi. As pg progresses the relaxin hormone starts to kick in and make our ligaments get ready for the birth in some women this will be mild but in others it can get quite severe to the point of pelvic instability. Your pelvis starts to separate at the pubic bone (if you have a feel on your pelvic bone, right in the middle it may feel like there is a small gap). It is mighty unconfortable and even very painful, but unfortunately there isn't anything we can do about it. What we can do is to pay attention to how we move around to try to lessen the pain we feel. I found that sleeping with a thin pillow between my legs helped a lot, as did resting on all fours, with my head slightly down to get the baby to move up off the pelvic area.

HTH