mmm, not sure how common it is but yes it happened recently to a friend. She was told several times they were having a girl, decked the room out in pink etc, only to have a little boy come out instead!!!!

Evidently if they tell you it is a girl, it could still be a boy as the 'bits' coudl be hiding. But if they tell you it is a boy, it definatley is a boy!!

good luck xxx