Hi JellyBean,

The pillow between your leg is meant to keep your pelvis and kness in line with your shoulders and therefore better posture for your spine. I've been having back problems for years and sleeping with a pillow between my knees has become second nature and I can't sleep without it! Make sure the pillow is not too flat, otherwise it won't work as it should.

I bought a half body pillow and its working great...I thought it would be more practical and easier to move around than having a whole body one...one half covers my belly and its long enough to go between my knees... I also put a pillow under my knees when on my back...

Hope it helped!