Exercise is good for healthy pregnant women who are receiving prenatal care. Try to do at least 2½ hours a week of moderate exercise. One way to do this is to be active 30 minutes a day, at least 5 days a week. It's fine to be active in blocks of 10 minutes or more throughout your day and week.

Exercise can improve your posture, relieve back pain and other discomforts related to pregnancy, and prepare you for the challenges of childbirth. Most women can begin or continue to exercise during pregnancy. Try exercise classes designed specifically for pregnant women or classes that offer safe variations for pregnant women. Many pregnant women find exercising in the water, such as swimming or water aerobics, most comfortable.

Moderate exercise/activity is safe for most pregnant women. But it's always a good idea to talk to your doctor before you start an exercise program.

Stay at your prepregnancy level of fitness

In the early stages of pregnancy, some women can continue their prepregnancy exercise routines (including running, aerobics, biking, roller-skating, skiing, weight lifting, or other physically strenuous activities). Other women find it necessary to take it easy during the first weeks of pregnancy but can return to their usual exercise after their morning sickness or extreme fatigue subsides.

While you are pregnant, listen to your body.

When you're fatigued, take it easy, but don't become completely inactive. Mild to moderate aerobic exercise, such as walking, helps your mood and keeps your energy up. If you like regular strenuous exercise, pay attention to your body's signals to gradually slow down or change your routine as your pregnancy advances. Fuel your body

Eat a small snack or drink juice 15 to 30 minutes before you exercise. Do not exercise on an empty stomach. If you have not eaten, your body may run low on glucose, causing your liver to release substances known as ketones or ketoacids into your blood. Ketones are harmful to a fetus.

Continue to eat a balanced diet. Pregnant women who do not exercise require an additional 150 to 300 calories a day. When you exercise during pregnancy, increase your caloric intake.

Stay hydrated and avoid overheating

Do not become overheated while exercising. To avoid dehydration, drink plenty of fluids before, during, and after exercise. Continue drinking liquids after exercise even if you do not feel thirsty. This will help you stay hydrated.