Great pregnancy exercise: Low-impact aerobics

The benefits of low-impact aerobics during pregnancy
Aerobic exercise strengthens your heart and lungs and helps maintain muscle tone. As long as you choose exercises that are low-impact — meaning no jumping, high kicks, leaps, fast running, and so forth — and keep one foot on the ground at all times to minimize stress on your joints, you should be able to continue your routine throughout most of your pregnancy.

Although exercise DVDs you can do at home are good when you're pressed for time (or just too tired to make it to the gym), consider joining an aerobics class designed especially for expectant moms. You'll enjoy the company of other pregnant women and the expertise of an instructor who understands how to keep you and your baby safe. (Many community recreation centers offer prenatal exercise classes.) If you're already signed up for a regular aerobics class, let your instructor know that you're pregnant; she can suggest ways to modify movements that may be unsafe or too strenuous for you.

First-trimester tips
Dress in layers of breathable clothing you can peel off as the intensity of the class increases. If you're huffing and puffing too much to carry on a conversation, stop; that's a sign you're exercising too intensely. Read the 13 rules of safe pregnancy exercise for more tips.

Second-trimester tips
Keep a bottle of water close by during class; dehydration can cause muscle cramps and in extreme cases even premature contractions. While there's no official recommendation about how much water pregnant women should drink while exercising, James M. Pivarnik, Ph.D., of Michigan State University suggests following this guideline: Drink one cup (8 ounces) before you exercise; one cup for every 20 minutes of exercise; and one cup after you finish your workout. In hot and/or humid weather, you may need more.

Remember that it may be harder to keep your balance as your belly expands. Use caution as you move across the floor. You may want to try a prenatal water aerobics class if one is offered in your community. It offers many of the same benefits as aerobics on land — a workout for your heart and body and the camaraderie of other expectant mothers — without the stress on your joints or the risk of injury or a fall.

Third-trimester tips
By now your pregnant belly is probably hampering some of your movements. If it feels too tricky or uncomfortable to bend or reach, just march in place. It'll keep your heart rate up while you take things a little easier. It's also best to avoid bending over, spinning, or any turning movements that may make you dizzy and cause you to lose your balance. Learn how to spot other signs you may be overdoing it.