Pregnancy or too much cake?

I seem to be at the point in life when everyone I know is either pregnant or planning to be pregnant. I appreciate that this is supposed to be a joyous time, when happiness bounces off the walls like an out of hand squash game, but to me it's a social minefield.

What do you do when someone waddles up to you with a slightly pronounced belly?  Do you say something like "When are you due?" and receive an evil, cold stare and realise you have just called them fat? Or do you say nothing (usually after several interactions like the one just described) and disappoint the proud pregnantee who has been trying to push out their modest bump to entice someone into a conversation about morning sickness, heartburn and swollen ankles brought on by their little parasites?

If only someone had produced a guide to the differences between pregnancy and too much cake...

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