Overview

Exercise is good for healthy pregnant women who are receiving prenatal care. Try to do at least 2½ hours a week of moderate exercise.^{footnote 1} 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 or midwife before you start an exercise program.

Stay at your pre-pregnancy level of fitness

In the early stages of pregnancy, some women can continue their pre-pregnancy 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.
• Remember that you can feel off balance as your body changes with pregnancy. So be extra careful when you do any exercise in which you could lose your balance.

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. In general, pregnant women who do not exercise require an additional 340 calories a day in their second trimester and 450 extra calories a day in their third trimester.^{footnote 2} When you exercise during pregnancy, you may need to 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.

Be careful

To prevent fetal injury, avoid sports that can involve potential contact, such as ice hockey, soccer, and basketball. Vigorous exercise above 1800 m (6000 ft) and scuba diving can be dangerous for your fetus.^{footnote 3}

Unless you are a competitive athlete, avoid strenuous activity, and exercise only in moderation. You should be able to talk while you are working out. Do not exercise to the point that you feel tired.

Stop what you are doing and contact your doctor if you notice any of the following:^{footnote 3}

• Excessive fatigue or shortness of breath
• Pain or cramping, especially in the back or pelvic area
• Vaginal bleeding or rupture of the membranes
• Dizziness
• Pounding heartbeat (palpitations) or unusual sensations in your chest
• Persistent contractions

After your fourth month of pregnancy, avoid any exercise that requires you to lie flat on your back on a hard surface, such as sit-ups and some yoga poses. The increasing size and weight of your uterus will press on the large blood vessel that returns blood from your lower body to your heart.

As your pregnancy advances (usually during the second trimester), unstable joints, an expanding abdomen, and an altered centre of gravity can make you more unstable on your feet. Also, by then your uterus is mostly above the protective circle of your pelvic bones. Avoid exercises that might cause you to fall, such as skiing or roller-skating.

Swimming and brisk walking are safe exercises throughout pregnancy.

General guidelines

Remember:

• Do not start a new or more strenuous exercise program without first checking with your doctor or midwife.
• Do not use exercise to lose weight.
• Avoid exercising during hot, humid weather or if you are not feeling well.
• Discontinue dangerous sports, such as horseback or motorcycle riding, water-skiing, diving, parachute jumping, or scuba diving.

There is no evidence that exercise causes miscarriage. But if you have a history of repeated miscarriages, your doctor may advise you to avoid exercises that require your body to bear extra weight (such as running) during the first trimester.

Your baby will not be harmed if you can't exercise because of a complication of your pregnancy or an existing chronic illness or condition. You may be able to do simple exercises in bed, with your doctor's approval.