Introducing dog to newest edition

A new baby is a very sensitive case that should be handled 100% right.
I don't know much about that, but I can give you some tips:
Get your dog used to babies, in the annoying aspect - Get him used to slaps in his face, pulls in his wag or legs, getting used to someone less familiar getting into his own place or mat. That's because little kids and babies don't really know how to be gentle, and their way of touching may be different and new for him.
He may be jealous, he may try to seek for your attention, and may see the new member a threat for him. You have to show your dog that his position is safe, that he still gets his quality time with you and that he isn't left alone.

Also, inviting a professional to introduce you the first steps would be great.