My 2 cents.. I always slept on my left side when I was pregnant 3 yrs ago, and to date I have sciatica pain on my left side (around the left hip area). i dont know what is the treatment for it. I try to sit properly with my posture correct, but in vain. So, all pregnant ladies out there, be careful about sleeping all night on one side and consult your gynac about any such pains in your body.