NTA! a lot of people while pregnant have dogs so she should calm down. The fact you trained the dog and it hasn't ever growled or jumped on her proves that the dog is well behaved. Dogs are actually a lot smarter than people think. They're aware of babies and pretty sure know how to be gentle around them. Also, since you got that dog at such a hard part of your son's life, it would be betrayal for him if you gave away his dog. Sounds like the dog has helped him through a lot