I was told that a good sonographer knows what to look for to make a fairly informed decision, rather than just a lack of penis etc for a girl. (ie. there are 3 lines that they look for in a little girl)

I was still worried up until the moment that Maddy was born that she might turn out to be a boy when we had prepared for a girl, despite three u/s from 20weeks plus telling us it was a girl. *L*