The WHO disagrees with the ADA, recommending a max of 30lbs of gain for the entirety of a pregnancy. Also, you aren't supposed to gain more than a pound in the first trimester, people, and not much in the second!  At the end of the second trimester, the baby, placenta, and fluid weighs about 3lbs, altogether.  You might have gained 6-10lbs by then.  You don't gain much until your 3rd trimester, and then you gain about a pound a week, a tiny bit more in the last 6 weeks.  And a good part of that is fluid because you don't eat an extra 500 cal a day until the VERY, VERY end.