No need for a new maternity wardrobe yet? Don't worry. Plus-size women may not gain as much weight during pregnancy as normal-weight or underweight moms-to-be -- and this is totally fine and should have no impact on your baby's development. We've seen larger women gain as little just five pounds, or in some cases, even lose weight, while they're expecting. Here's why: During pregnancy, very little of the weight you gain goes to the actual growth of your baby. Most is used to build up fat stores so you have energy for the challenges that lie ahead (i.e., childbirth and nursing). If you already have enough stored, you won't pack on as many pounds as women who need to gain more. It's also quite normal to lose weight during the first trimester, regardless of your body type. As many as 80 percent of moms-to-be experience some form of pregnancy nausea, which can make keeping even the blandest food down a real challenge -- resulting in some looser-fitting jeans these days. Talk to your doctor if you're concerned about your lack of weight gain. He or she can do an ultrasound to reassure you that your baby's growing normally.