I agree with the people who say it is just not worth the risk to keep this dog, so I won't reiterate what they have said. But I do want to address those who suggest that you work with the dog, get specialized training, and carefully monitor the child/dog interaction. From my experience (we adopted a rhodesian ridgeback - which are supposed to be very family oriented - when my first son was three), none of this is very practical. Motherhood will take pretty much everything you have (especially if you are a new mom) and you will be tired, distracted, confused, and at some points, overwhelmed. All of this is manageable, unless you have something major thrown in with it. This is what happened to me. I thought by waiting until my son was three to get a dog, I would be able to devote the time and attention necessary to the dog. But it was sooooo stressful, and this dog had never even shown any signs of aggression. But he was big, and his paws or bites could have caused serious injury to my son, regardless of the trigger. And it is hard enough to keep up with a crawling/walking toddler who is getting into everything - do you really want to add dog-related issues that you will have to monitor?
The other consideration (I don't know if this is applicable to your dog) is that my dog was so big/strong that everytime he spazzed out because the doorbell rang or the garbage man came, he would knock over lamps or other furniture. I barely caught a lamp before it hit my son! Yes, I know, the answer to this is training, but THAT'S MY POINT!! I didn't have time, energy or patience to work with the dog. In the end, we returned the dog, and I have felt terrible about it, because it wasn't the dog's fault, it was mine for not understanding what a challenge it is to mix kids with dogs. Just something for you to chew on. (no pun intended!) Good luck!