Dr. Elizabeth Pryor answers the question, How can pregnancy alter my exercise regime?


I'm 11 weeks pregnant, and I take a high-impact aerobics class three times a week. I've been feeling more winded and thirsty by the end of class, but I'm still able to finish. I also go to a weight training class twice a week. Can working out and lifting weights have an adverse effect on my pregnancy?


You should expect changes like you're experiencing during pregnancy -- even early in the pregnancy. Hormonal changes that affect the heart and lungs are already in place during the first trimester. Moderate exercise is recommended for women who are already in fit condition prior to pregnancy.

Many studies have shown the benefit of exercise during pregnancy. In the absence of obstetric or medical complications, pregnant women who engage in a moderate level of physical activity can maintain cardiorespiratory and muscular fitness throughout pregnancy and the postpartum period. However, pregnancy-related changes may interfere with the ability to engage safely in some forms of physical activities.

Performance tips

Most women who perform regular weight-bearing exercise prior to pregnancy note a progressive decline in performance beginning in early pregnancy.

  • Exercise regularly (at least three times per week) -- this is preferable to intermittent activity.
  • Keep your target heart rate at 140 beats per minute or less.
  • Avoid exercise that requires you to lie flat on your back after the first trimester. Such a position is associated with decreased cardiac output in most pregnant women.
  • Eat a good diet. Pregnancy requires an additional 300 calories per day. Women who exercise during pregnancy should be particularly careful to ensure they're eating an adequate diet.
  • Resume exercise gradually after pregnancy. Many of the changes of pregnancy persist four to six weeks postpartum. Prepregnancy exercise routines should be resumed gradually based on your physical capability.

Safety considerations

  • The amount of oxygen available for aerobic exercise decreases during pregnancy. Be aware of this fact, and modify the intensity of your exercise according to your symptoms.
  • Stop exercising when fatigued and don't exercise to exhaustion.
  • Take care to not become overheated when exercising during the first trimester. This can be maximized by adequate hydration, appropriate clothing, and optimal environmental surroundings during exercise.
  • Weight-bearing exercises may, under some circumstances, be continued throughout pregnancy at intensities similar to those prior to pregnancy. Non-weight-bearing exercises such as cycling or swimming will minimize the risk of injury and facilitate the continuation of exercise during pregnancy.

The bottom line

Depending on the individual's needs and the physiologic changes associated with pregnancy, women may have to modify their specific exercise regimens. Ask your doctor about prenatal exercise classes in your area that are designed to help with stretching and breathing -- providing an added bonus at the time of labor and delivery.

The information on this Web site is designed for educational purposes only. It is not intended to be a substitute for informed medical advice or care. You should not use this information to diagnose or treat any health problems or illnesses without consulting your pediatrician or family doctor. Please consult a doctor with any questions or concerns you might have regarding your or your child's condition.

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