It would have to raise your body temperature a few degrees, which would also make you uncomfortable. I just wouldn't turn your heating pad to high, maybe just keep it on low or medium heat.
The only reason why I'm skeptical is because I heard that if you take to hot a bath and change your body temp it will hurt the baby so why wouldn't a heating pad?
It's safe to use... I tried one yesterday and it definitely helped my back, but I doubt think baby boy liked it very much! He pretty much immediately started pushing out toward the front and stayed there until I stopped using the heating pad! Lol!
Yes , thats what I need to be using. My back is killing me!