My bestie is the opposite right now. 5 months in, she was still at her pre pregnancy weight. Fortunately, since she was healthy before she got pregnant, her baby (my niece!!!!!! Yay!) is fine.  She's since started gaining weight after her OB found a medication that actually helped her keep food down, but she told me that, if she wasn't already healthy and active, her OB said her baby could've been in serious trouble.  It's not just important to be healthy during pregnancy. You've also got to start before getting pregnant. She worked for months to get her BMI up and BF% down before trying for a baby. Lard moms? The only exercise they get is from stuffing their faces and walking to and from the kitchen.