[NY] Pregnant & Interviewing

I quit my job last July to alleviate the stress of going through IVF (and it was a toxic work environment). I’m now pregnant (19 weeks) and have an interview lined up.

Do I need to disclose this to the employer during the interview process or only if I receive an offer? Can they legally not hire me if they knew I was pregnant? Or would that be considered discrimination?

What’s the best way to approach this, and how should I address the long gap in my unemployment?