Maintain at least a moderate level of physical activity. From M.D.'s to midwives, R.D.'s to R.N.'s, the consensus is to keep weight gain on track with regular exercise, ideally for at least a half hour three times a week. "You can safely do prenatal yoga and light weight training, and use cardio equipment like elliptical trainers and treadmills," notes Dr. Ricciotti. Start slow, avoid overheating, and talk to your health care provider, especially if you haven't been exercising. For the out of shape, the best bet is to start a walking program, which is always safe during pregnancy. If you're starting out your pregnancy in good physical shape, daily vigorous exercise is fine as long as you avoid activities that can interfere with balance, cause injury to the abdomen, or have a high risk of falling. These include skiing (both water and downhill), surfing, horseback riding, cycling, diving, and snowmobiling. And there's more to pregnancy exercise than meets the scale: That added muscle tone and stamina may well help you endure the rigors of labor, too.
Ditch (some of) the desserts. As with any real-world diet, thinking you're never going to be able to treat yourself is bound to backfire. "Being pregnant may not mean having dessert at every meal, but it also doesn't mean you have to be perfect," notes Dr. Ricciotti. Have some cookies or ice cream in moderation two or three times a week if you're on track weight-wise. Or buy yourself a box of really good chocolates and savor one each night before bed.
Take care of yourself. While plus-size women are at greater risk of pregnancy complications, being overweight isn't a reason to avoid getting pregnant. And the last thing you would ever want to do if you're gaining too quickly would be to go on a crash diet. Ideally, the health risks to a baby will be an incentive to eat healthfully and be vigilant about prenatal care. "Start a nutritious eating and exercise plan now," adds Lewitt, "so you can have the best possible outcome for your baby."
Stephanie Wood, a mother of three, lives in Blauvelt, New York, and writes frequently about pregnancy and parenting. She is the coauthor of The Epidemic.