I'm a medical student looking to plan (as best as possible) a baby during 3rd or 4th year. A large question that has come to mind is whether or not being pregnant during audition rotations is advisable. My concern is that I will likely be going into a more competitive field like surgery where automatic bias may be applied to be despite my worth ethic if I am pregnant at the time.
I can't comment about perceptions of you but do want to say that if this is your first baby, you likely won't show until 20 weeks or more. Plus, scrubs are incredibly forgiving, especially if the people you are with don't know what you look like at baseline.
I was pregnant during the summer as fourth year of medical school started so I was trying to get letters from people as I also was exhausted and slightly nauseous constantly. However, no one knew I was pregnant since I didn't tell them and tried to hide my exhaustion as best as possible. Very true re: scrubs being able to hide a pregnancy, especially a first pregnancy. I'm pregnant with my third and wear scrubs every day and just over the last few weeks have patients started noticing that I look pregnant (I'm 24 weeks along).
Ditto to the answers that you can hide it for quite a while...
I'd also say that it'd personally make me question whether I'd want to go to a program that had biases against women with families despite the clear evidence that I was a hard worker. I know that that could be particularly difficult in competitive fields (like surgery) that have been, traditionally, less friendly towards women overall to begin with and that it's considerably easier for me to say as someone who's going to apply in peds. That said, I still feel like that kind of attitude says something about the support of the program in general and just the kinds of people you'll be working with on a daily basis.
I do get your concern though and can't 100% say if I wouldn't feel similarly if I were in your position. And if it helps, I've heard the residency directors at my program (highly ranked med school in big non-kid-friendly city) talk about this issue and they have all said (and sounded like they truly meant it) that it's not a problem to start a family during residency. Some did mention that the interview is not a good time to bring up your child-bearing plans, but I suspect you already knew that