Because, I don't know about you, but I pretty much won't ask a woman I don't know about her pregnancy unless a) she's wearing a T-shirt proclaiming her current state or b) the baby is crowning while she breathes through the labor pains. Anything else is just risky.
I've heard a bunch of stories lately from people who asked others about their pregnancy, including a guy who was attending a wedding with his wife. Trying to make conversation with a couple at their table, he asked the woman, "When are you due?" and was mortified when she answered in a frosty tone, "I'm not pregnant." There is just no recovering from that, and the poor guy spent the rest of the reception not speaking to the people at his table.
And Kat's lil sis is still miffed at the fast food worker who, six weeks after she gave birth, looked her stomach and inquired about her due date.
Although I was surprised someone had the guts to ask about my pregnancy, I wasn't offended. It means I no longer look like I'm just packing on the pounds, but the weight gain actually looks like a pregnancy. Now, strangers coming up and touching my belly? That's a different story.