A baby in my shirt

So, yes I am 8 months pregnant. I also am in the primary in church, so I help in teaching the kids. This Sunday I found myself giving one boy in particular special attention (you know going to class and such, not sitting in the hall). I think I am pretty lenient when it comes to kids, I don't expect them to do any more than adults would do, so if they are talking quietly, fine, if they are standing quietly, no problem, I've taught adults and they don't sit quietly and look at the teacher, why should I constantly prod the kids to do the same? Anyway, I found myself behind a class where the aforementioned boy was residing (not necessarily quietly) and had the following conversation
Girl: Is that your first baby (she has 4 younger siblings, she knows what is going on)?
Me: Yes. (short and truthful)
Boy: What baby?
Girl: (pointing to my belly) That one.
Boy: There's a baby in your shirt?!?
Me: ... (technically)
Girl: Not her shirt her belly.
Me: (is a response necessary?)
Boy: So it's like alive but not.
Me: Shhhhh.. turn around and listen. (who controls these children oh yeah supposedly me for two hours)