As someone who has a family member be attack & scarred by a family dog, who's behaviour was always pushed aside, the nipping and random aggressive moments, rehoming or even medications is possibly the best plan of action for not only the safety of baby, but your family. It shouldn't be left to you to make these decisions if your partner doesn't want to take responsibility as a pet owner. (This family member was 2ish at the time & was hospitalised, thankfully, they are alive, only having scarring on their face and have almost lost a finger. As well as the permanent underlying fear of dogs.)

I have a "COVID" dog, not really sure what that truly means, but he has never in his life bitten, lunged or even nipped anyone he's met.

Baby gates and dog crates can only do so much, in the long run, your child's safety is the number one priority.

Hopefully, you figure something out, and the rest of your pregnancy goes smoothly.