Pay attention, folks, because I'm going to give you a piece of advice that, if heeded, will keep you from looking like a socially inept moron and possibly extend the length of your life (or at least keep it from being cut short). You ready? Good.
You're just absolutely sure that little bump under her top is a pea in the pod. And sure, you think she has a lovely glow that could only mean motherhood. Perhaps you pride yourself on your ability to spot a pregnant belly earlier than anyone else can. Fine. Now listen to me:
NEVER ever ever ever ask a woman, "when are you due?" Or the more obvious, "are you pregnant?"
I don't care if she looks like a beached whale and you could have sworn you just saw something kick. There is at least a 50% chance that she will NOT be pregnant, and you will have unwittingly told her that she looks...well...pregnant...which translates to fat. And even if she IS pregnant, she'll never be as far along as you think she is, and she won't enjoy thinking she looks as far along as you think she does. Trust me.
And if you think your radar picks up pregnant woman and decide to throw caution to the wind and make this terrible social snafu, and she turns out to (surprise!) not be pregnant, whatever you do, DO NOT follow up with, "are you sure?"
Got that? Excellent! You will probably live a long and fruitful life.