They say you only need an extra 300 calories a day during pregnancy. But you're also supposed to gain one pound a week the last 20 weeks.
One pound=3500 calories
3500 calories divided by 7 (days in the week) = 500
So you REALLY need an extra 500 calories a day.
Good. Now I don't feel so bad about all the mint chocolate oreos I've been eating lately...