Things (that people have actually said to me in the last week) that are okay and not okay to say to a pregnant woman.

It's okay to say "When is the baby due?"

It's not okay to follow that question up by saying "Oh! Is it twins?"

It's okay to say "You look great!"

It's not okay to ask "Are you married?"

It's okay (but a little weird) to ask "Can you HEAR the baby?"