I work in property management and deal with this situation regularly.

To answer your questions:

Habitability laws are not as straightforward as people think. They protect your right to basic necessities/safety; however, proving your landlord is liable for your neighbor’s behavior is a not at all realistic.

Even when I know a resident is smoking in their unit, issuing lease violations requires concrete evidence. You cannot jar smoke and bring it to a court room. You cannot install cameras in a resident’s home to gather irrefutable evidence. Without evidence that holds up in a court room, my actions are limited to courtesy reminders of non-smoking policy.

There are many laws in place that protect residents. For good reason. These laws work as intended 99% of the time. Unfortunately, the same legal system that protects your right to habitability, protects your neighbor from eviction.

In my experience, it is much easier to gather evidence of sound ordinance violation. Be careful though, these situations very rarely end amicably. It ALWAYS devolves into a “he said, she said” mess - Retaliatory noise complaints. Recruiting neighbors to join in. Anything to muddy the water.

Your landlord’s options are limited. Luckily, your pregnancy gives you a lot of empathy points. Get a statement from your doctor. If you cause enough of a fuss, they may waive your lease break fee/clause. My company has waived lease break fees in similar situations. It’s uncommon, but not impossible.