q, you're obviously showing, right? are you showing for 2? i had a similar sitation when i was pregnant. i interviewed, they knew, because they asked me when i could start, and the next orientation was 3 days after my due date. so i guess i mentioned it (if they hadn't figured it out). but can they say, 'oh, it looks like you are pregnant (what if you're just overweight?? :smackingf ). i ended up cutting my maternity leave short, and taking on a full time job, that was too much for me, and ended up leaving.
i would think, like any other situation (like if you live very far, or don't own a car), the question posed may be "is there any thing that may prevent you from doing your job to the fullest (or fulfilling your commitment)?" i don't think they would flat out ask if you'd have any schedule conflicts. who knows, they might ask what days/hours you prefer (depending on the flexbility of the position). i recently interviewed for a position that would have required me to follow one preceptors exact schedule, without exception. the nm knew i was in school, and could not guarantee me off on those days. so that was the end of the interview (didn't even get into the childcare thing).
in my most recent interview, a lot of my 'personal' life came up, kind of in conversation. i casually mentioned having a child, so they asked a little later about that (but in a very casual tone). let's face it, they want someone who's going to be able to work, but have to beat around the bush a bit.