I had the same question awhile back, both with regards to away rotations and interviews, as I'm nearly 22 weeks pregnant. Everyone I have talked to about this has assured me it won't be an issue. My mentor was pregnant during her Ob/Gyn interviews and (anecdotally) I know of several residents who have been in the same position without any problems. Besides, if there was a particularly malignant program that harassed residents for having families, would you really want to be there?
Good luck! Would love to hear other opinions from people who have BTDT.