Don't make a fuss of any introduction.
When you and your baby come home from the hospital, treat the dog exactly as you normally would. Come into the house and do what you'd normally do, carrying the baby in the carseat. Make a cup of coffee, sit down for a while until the dog has adjusted to you being in the house again. Don't over fuss over the dog more than you normally would.
Once the initial 'coming home' excitement had died down, a very low key introduction could happen. It won't be necessary I don't think, your lovely dog will have absorbed the arrival of the new thing as just that. A new thing which has it's own place in the house.
Whatever happens, don't over compensate for the change, or make a fuss about it. The dog will fret if he works out that something new has happened which he has no hope of understanding, but can feel through your actions is important, worrying and possibly stressful.
Treat it as a normal, no drama, calm thing and your dog will too.
As an aside, the pack theory has been discredited by many, many people as a dated method of dog training and treatment. It really would be worth posting something about this in the doghouse section for more advice.