Stranger asking if expecting or not, Rude or Not?

Out with kids for the day, a stranger begins yelling at her kids, immediately after I hear this same loud voice asking are you expecting? I was in total shock and continued to speak to my child because maybe she wasn't speaking to me. I look up and she asks again. Since it was sudden and the verbiage of the suggestion was "Excuse me, are you expecting" I put on a polite defense answer "Yes, thank you", and her response was "God Bless" from here I gave a nod, I really wanted to end the engagement to remain polite. My bump is obvious at this point. However, how would you respond to this?