My puppy is sweet but I'm concerned about a new baby on the way.

I am having a problem with my 2-year-old mixed breed dog. We got him 6 months ago and got him fixed. He sleeps with our daughter and if anyone goes in there at night to check on her, he growls and will try to bite us if we don't use a firm voice to tell him no. What can I do to get this behavior under control? Should I stop letting him sleep in her room and not allow him upstairs at all? Thanks.

How can we introduce our 6 yr. old dog to the new baby and still make the dog feel comfortable and loved? He has been the baby for so long and we don't want him to feel threatened in any way.