Thanks everyone, this is good advice. You reminded me that this is something good. I've been so worried about how this could affect my career that I haven't had much of a chance to be happy about it.
anxious_one, I do have a sense of the anti-children hardliners are and, unfortunately, one of them is my advisor. I have a great relationship with him, so hopefully that will count for more than my "accident" (and that's really what it was).
fuzzy, the students in the department who had children during the program are male (there's a double-standard there), so it was more or less overlooked. It would still be good to talk to them, though.
I'm not that far off from finishing and I don't think this will slow me down much.
I will post an update when I decide to tell my advisor. Meanwhile, I'll try to wear loose clothing.