I had to get us every week from 28w with Haz, and will probably be the same with this one due to my anti-e. It wasn't so much the back pain but it made me feel sooooooo sick. It was restricting the blood flow and I was getting horrible hypotension from it. When bub started to engage, it made it way easier because I could lay on my left side without it obstructing anything - they were checking bloodflow through the brain. Ask if there is anyway they can do the US with you on your left side - its the best position for a heavily pregnant woman anyway.