Aggression is not normal for pregnant bitches if anything my dogs get a little more desperate for attention. You could have a few things going on and I assume this is a new dog to you and you got her pregnant.
She could be having a false pregnancy
She could be pregnant an x-ray will determine that from your vet and also give you about how far along she is.
Now you have to deal with the aggression towards your kids. IMO I would not have a dog around my kids who could hurt them and your females does not have the correct temperament for an APBT
So you can put her to sleep or keep her away from the kids at all times but keeping her in a dog run or kennel. If you do keep her you could abort the litter since temperament is passed down to the offspring.
You have some tough choices to make but please understand the growling at your kids is not normal or a pregnant pit bull.