Most of the time when you are pregnant - especially toward the end of your pregnancy - people notice. For me, it was very obvious. Because you are pregnant you sort of expect people to be nicer to you (e.g., hold the door while you slowly waddle to it from 20 feet away) and to ask all sort of questions (e.g., are you planning on having a natural birth?).
Now that I am no longer pregnant I sort of forget that all of these people that see me every day knew that I was pregnant. I am always shocked when someone in my office that I don't know goes beyond a polite greeting and asks me about my baby. "How do they know I recently had a baby?" I wonder. "Can they see my skin pouch?" Or worse, "AM I LEAKING?!?!" Then I recall that 4 months ago I was large and waddling and since I no longer am these people correctly assume I gave birth.
Little do they know that just by asking they are opening themselves up to having to see pictures of my daughters. Like all of you folks.