Many women who exercise regularly do it to lose weight, or to keep from gaining. That’s a good strategy, since a lack of adequate activity plays a big part in America’s obesity epidemic. But the rules are different when you’re expecting — the most important difference being: You’re supposed to gain weight during pregnancy. If you’re eating the recommended number of calories per day (from the right foods), and exercising for at least 30 minutes on most days, Mother Nature will work out the math and you’ll gain the right amount of weight over the course of your pregnancy.
Pregnancy weight gain is variable, not just from one woman to another, but also as a pregnancy moves along. (For more details, see the Pregnancy Diet.) You’ll gain more weight in the second and third trimesters than in the first, and the more you exercise, the more calories you’ll need to consume (now that’s a challenge you’re up to!). A sedentary 140-pound woman needs only about 1,680 calories a day during pregnancy, and if she takes in more she’ll gain too much weight. That same woman, though, when she’s moderately active on a consistent basis, needs 2,100 calories a day to maintain proper weight gain. The difference is a whopping 420 calories a day (try to cash it in on something healthy — a frozen yogurt topped with trail mix sounds good after a workout). Very active women may require even more calories.
The best way to measure if you’re eating the right number of calories for both your baby and your pregnancy exercise routine is to monitor your weight gain. If you’re gaining too much weight, you’re giving yourself too much (calorie) credit after your workouts. If you’re not gaining enough, either you’re not compensating for the calories you’re burning — or you’re burning too many. Adjust accordingly to get your weight gain back on target. Small, frequent meals and regular fluid intake throughout the day is the best eating formula for all pregnant women — but it’s especially smart on days when you exercise. That way, you’ll have a steady flow of nutrients to help you keep up your energy, without the discomfort that can come from exercising on a full stomach. Heartburn during pregnancy is no fun, and heartburn during your afternoon aero(burp)bics class is worse!