Eating for two? Despite what you might think, this doesn't mean you should overindulge. "In the first three months, your calorie intake shouldn't increase at all, but your nutrient intake must, especially when it comes to folic acid, iron and calcium," says Elizabeth Somer, dietitian and author of Nutrition for a Healthy Pregnancy. "In the last two trimesters, your calorie intake only increases by 300. So every single bite is an opportunity to nourish you or your baby." This means thinking before you snack, rather than grazing your way through the junk food in your kitchen.