While I don't pretend to be the owner of a Fila or an expert by ANY means, I would also recommend against a Fila for your situation, unless you've got prior experience with a dominant, potentially agressive and VERY strong dog! You don't mention if you've had dogs in the past, or which kind if you have. These dogs definitely require a serious handler. I don't know how much you weigh, but can you imagine a dog that potentially outweighs you by 20 pounds or more going after someone while you've got a small boy and newborn in tow?
I have a Newfie mix, and although he is the sweetest, most gentle and LEAST aggressive dog on this planet, he serves as a strong deterrant when we go for walks. Most people are cautious about approaching ANY dog, especially a large one. Rebekah is right, Filas are serious dogs and have a very serious nature.
Honestly, I would have a Pitbull around my children and family before I'd have a Fila. Pitbulls are extremely family oriented and ADORE their people, particularly children. But once again, they require an experienced owner. I think that the first question you need to ask yourself is how much energy and time you want to put into training this dog. Its IMPERITIVE that dogs with protective nature's be under control, without fail. That requires a serious amount of handling and working with your dog.
Not trying to deter you, per se, just sharing what I've heard about this breed. I know a guy that has one, he's a single guy, and spends lots of time working with the dog so that he is absolutely positive the dog has perfect recall and is under control around strangers. I can't imagine being able to put that kind of traning into a dog AND having a new baby!
Just two cents! Good luck with whatever you choose!