Congrats on your call-back! That's really exciting.
I was/am still in the same position and decided to keep it to myself during the interview (I wasn't showing), but bring it up when they offered the job. This is because (1) the jobs have a 6 month probationary period that will still be in effect when I'm due, (2) you have to work for an employer for 1 year before qualifying for FMLA and that's something that I definitely want, (3) I'll only have 2 days of sick leave when I'm due and no annual leave, and (4) I'd like to be able to go part time for a while after leave. Technically, (and I think especially if we started off on the wrong foot) they could just get rid of me within my probationary period even if I accepted their offer.
Telling them when they make the offer means we can negotiate on this stuff and I can get in writing that they will honor my leave. I also don't have to feel like I'm hiding something from my new employer or feel like I'm leaving them in a tight spot when the time comes. By law, you don't have to tell them and they can't make hiring decisions based on your pregnancy so I don't think you should feel bad if you decide not to. It's awkward, isn't it? The good news is that I have revealed my pregnancy twice and in both cases was able to negotiate concessions - so in my career area at least this strategy works. In both cases I decided the jobs weren't a good enough reason to not stay at home, but I'm still looking for the right job. I expect it will get harder and harder the closer December/January gets.
Good luck!
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