"I Only Gained [Insert Ridiculous Number] Pounds When I Was Pregnant!"
It's not easy for a pregnant woman to feel pretty while sporting stretchy pants, so take it easy with your weight gain/loss comments. While it may be true (although we'd like to see proof) that you gained a sprightly 12 pounds (5 kilograms) while carrying your first, second or third child, keep this little nugget to yourself. At least until we've retired our pregnancy pants.
There is, however, one exception to this hard-and-fast rule: If you want to regale us with tales of how you gained a portly 80 pounds (36 kilograms) during your pregnancy and then spent a subsequent two years taking it off, that's one story we don't mind hearing.