I don't know if it was ballet body, but there was a VFer who did barre while pregnant. She is an ex-Marine and used to do really hardcore workouts. After barre, she never looked back. She said they were the best workout for her body, and were surprisingly tough while being gentle on her body. If I can find her posts about it, I will post the links here. Hopefully she will chime in.
ETA: As I thought, it was neatski
Do a search on her name and you'll find her talking about barre3 and pregnancy.