When I was pregnant with DD my family believed you should never tell the names, incase the ultrasound was wrong about the sex!

We never found out that it was a girl anyway.
All I ever told my family was that the girls name was biblical (hannah), and the boys name is quite old (toby).

I did however say that we would be using our middle names for the bubs middle name.
So we got Hannah Marie, and if it was a boy it would have been Toby Leigh.