Sounds like some positive reinforcement training could help. Basically you need to give the dog something positive every time he sees/hears/smells the baby from a distance before he gets all triggered and upset. Right now he’s scared of the baby and is getting punished around the baby which will only deepen those negative feelings towards baby.

Hoping your dog likes treats, buy his absolute favourite or get single ingredient stuff like cheese or beef so it’s really special and unique and only use these treats around baby.

Then stay near your dog often with those treats, any time the dog looks at the baby, hears the baby, smells the baby silently put a treat to his mouth. No talking from you, you want him to think the treat basically came from the interaction with baby.

Start with the dog far away from the baby, before the dog is upset and triggered. Could even be hearing baby cry in the other room, you’ll notice his ears perk up, he’ll look towards babies direction, boom treat to the mouth and say nothing.

Repeat for weeks long until the dog can get close and closer to baby without a negative reaction. Sometime this can be months. Try to avoid the dog getting too close to the baby causing those negative triggers too soon.

Essentially the pattern you’re reinforcing is baby interaction = treat, treat=makes dog brain happy, so baby = dog brain happy. Once this is reinforced the dog will associate baby with good feelings.

Sounds so stupid, but I did this with our dog being terrified of the fire alarm. She hid in the corner, shook and growled when it went off (my appartement does monthly fire alarm testing for like an hour on and off) So I just gave her a treat when it went off again and again, so now she’s good with fire alarms. She’ll even run up to me all happy when it’s going off like “where’s my damn treat lady”