I have heard that quiet a bit actually.

When we had V we found out her sex adn the sonographer kept saying he and apologising because she said its just something that she does no matter what. Yep V came out a girl

BUT

We were told at 4 u/s that M was a girl (we had asked) and it wasnt until an emergency u/s at 37 weeks that we actually found out that he was a boy. That was very shocking!