Nope not at all Hackney, and part of me is swaying to find out so we can tell ds incase it's a girl as he is convinced its a boy.
Just thinking that a sibling may start to think of them as little "brother" or "sister" and think they are going to be lots of fun and not appreciate that there just a "baby" really when born and all babies kinda do the same boring stuff. That maybe doesn't make it any sense.
I'm just imagining though saying to older sib "oh your going to have your little brother/sister, won't that be fun" then when baby comes they think "no, they're not much fun, boring baby!"