They only say laying flat on your back needs to be limited after you are farther along cuz it puts pressure on your blood vessels and cuts off blood to baby and your lowere extremeties. I love laying on my back mostly cuz my hips kill laying on my sides. But it also irritates my little man so I can only stay for a little bit or he starts making things painful for mom
I lay on my back being elevated because laying on my sides hurt.