While your wife is in the hospital, take the dirty baby blankets home with you and put them everywhere the dog claims is his... He can already smell/sense the baby in your wife's belly... A baby will be proven to hold dominance by the way his/hers sent is placed in the dogs "spots" Including the dogs eating area. If the dog chews up any of the blankets, punishment/training will follow. When you bring the baby home, let your wife come in 1st... By herself. This way the excited dog will see the owner that's been gone for a few days. After, take the dog on a looooong walk while your wife brings the kid in and starts to relax. Then, slowly introduce them... Under no circumstance should you add anything new with the dog the day you bring the baby home. A muzzle is only going to add stressed and the dog will rationalize that stress with the new baby.
My wife and I had a 5 year old husky when we brought our 1st baby home... At the time, the dog was our baby... We stressed and freaked out over what he would do. I talked to a dog trainer and what I wrote above is exactly what they told me to do. It worked well, our husky was a little freaked out but he settled and it was over. The second kid, did the same thing and he was even better about it.
If the dog sees you as it's alpha, he will have to except the new member. It goes without saying though, never ever ever leave kids and animals unsupervised.
Sorry for the book, I just know how horrifying a baby and a dog can be... Just be calm and dominate and everything will be good.