It hurts me to think about this, but your tailbone actually straightens out almost completely while pregnant. It is definitely normal that it hurts a lot. I suggest using a donut pillow when you sit down on any remotely hard surface, but for me this does not help much. I have actually had tail bone pain for SIX years straight, and there is no real fix for it. I'm praying that once baby is born maybe a miracle will happen to me and it will have straightened out and then go back to normal. Ugh it is truly the WORST pain. Sorry mama. Definitely try a donut pillow though, or try kind of sitting to one side or the other as not to bother the tailbone which sits in the middle of the two.