I would have this conversation with your vet, and a pet trainer if possible, and there are probably books at the library that will cover this as well. Dogs will knock kids down, it's inevitable, so you have to be diligent about training your dog. The best part is, you have a bit of time before the dog and the baby will meet, so you have time to prepare your dog. I would say if you have friends with kids, or other kids in the family or there is a park nearby, get your dog around other kids, and often. Get him used to the sounds and actions of young kids, get him socialized with small children. Maybe the day your child is born your husband can take home a blanket that the baby was wrapped in (not the one your keeping as a keepsake!!)so the dog can get familiar with the baby's smell. I would think you should remain as normal as possible, and allow the dog in all of the same places as he is allowed now, if not this could cause jealousy. I would think you also need to train your child to be respectful of the dog and not pull on him, or tease him. You could probably also help, by (you) sticking your hands in his food bowl while he is eating just in case your child tries it. I truly think over time the biggest problem you may have is this border collie "herding" your child, and being protective over it. Another idea might be find some You Tube shorts on babies crying--I am sure they exist, and get the dog used to cries, as undoubtedly cries will scare, or concern him.
Finally, no matter how good you think your dog is, make sure someone is around the dog and the baby/child at all times. Afterall, they are still animals, but I think to get rid a pet just because you have a baby is wrong---a pet is family too (and was there 1st :), and maybe your baby will have a new best friend--in your dog )!!!!!!!!!!
Congatulations on your pregnancy!!