I would guess its tension, cause I feel the same, and if you think about it, its a bit like youre trying unconsiously to keep them in there and you put tension on you lower body, a tension that the body is not used to.
all the best
Ashavaki
Thanks, and good luck to you!
I would tell her just to relax. I go for my first beta on thurs.
This is my first IVF, I also had back pain a few days after the transfer. All I can tell you is that it is normal.