First off, congrats on the child and wanting to keep the family safe.
Now for a question that I always ask anyone who ask me about this is, "are you going to practice with it and shoot it a lot"? If yes, then a semi auto is fine, if no, "it is just for home defense", then I recommend a revolver.
If you are not going to shoot a pistol enough to know how to fix any malfunctions (stove pipe, double feed, jam, etc.) in a hurry, then that is not what I would want in a defensive situation.
For myself, I keep a 1911 in the nightstand and that is just to get me over to the closet where I keep a shotgun.
