All pregnant women are encouraged to participate in two types of exercise- aerobic and resistance (also called strength or weight-bearing) training. Combining both types of exercise creates the most effective exercise program.

Aerobic Exercise

Aerobic exercise includes brisk walking, jogging, swimming, dancing, and various types of aerobics classes. Aerobic exercise improves the fitness of your heart and lungs and helps protect against cardiovascular diseases. It increases your body's ability to use oxygen and it burns calories. Burning calories allows you to eat more and still maintain your weight.

This table shows how many calories you expend per 45 minutes of activity. Some exercise equipment calculates the calories you expend. Use that information to adjust your level of fitness.

Caloric Expenditure
Activity45 minutes
Walking (3 mph)150 calories
Jogging (5 mph)345 calories
Low-Impact Aerobics300 calories
Climbing Stairs300 calories
Dancing450 calories

Resistance Training

You are encouraged to combine daily aerobic exercise with resistance training of specific muscle groups. Resistance training builds muscle and slows bone loss, strengthening muscles and bones by exerting force on them. As you build muscle, you will improve your body tone and burn off fat. In addition, the greater your muscle mass, the more calories you burn during exercise.

Resistance training includes lifting weights-using free weights or machines-and doing such exercises as leg lifts or squats. Try to avoid exercising the same muscle groups two days in a row to allow them to recover between use. You will begin to see positive results when you do resistance training for as little as 30 minutes, two to three days per week.

Types of recommended exercise include:
Aerobic Resistance Training (2-3 days/week)
Stationary bikeWeights
Brisk walkingLeg lifts
JoggingSquats
Swimming 
Dancing 
Organized exercise classes 
Stair masters 

How to Get Started

First, discuss your current or proposed exercise program with your doctor. While most pregnant women will benefit from an exercise program, some conditions of pregnancy make exercise very risky. Certain individuals with hypertension during pregnancy, preeclampsia, cervical shortening, and placenta previa must talk with their physician first as exercise in most circumstances should be avoided.

Begin slowly if you have not been involved in a regular exercise program. Start with five minutes a day and gradually increase the time as your conditioning improves. The key to a successful program is persistence and consistency. Some people find that exercising with friends or acquaintances makes it easier to stay with an exercise program.

Exercise does not have to be expensive. Walking is one of the best exercises for anyone. Brisk walking can give a good total body workout and is among the easiest forms of exercise on both joints and muscles.

You also may want to consult books and videos or work with a personal trainer. Look for resources that are geared toward exercising while pregnant. A personal trainer can show you how to perform certain movements to avoid injuries and acquaint you with the equipment in the facility that you are using.

Remember that pregnancy alters your center of gravity, which may affect your balance.

Pregnancy may also increase your:

  • energy expenditure and need for increased intake of calories;
  • risk of dehydration, requiring you to take in extra fluids;
  • weight, making exercise more demanding on your system; and
  • risk of ligament, muscle, and tendon injuries because hormonal changes loosen your joints.

You should not exercise flat on your back after either 24 weeks of gestation or after the uterine size has reached the 24-week size, which may happen much earlier in multi-fetal pregnancies.

Begin each exercise session with a light warm-up for 5 to 10 minutes. Slow walking, low-resistance stationary cycling, or climbing a StairMaster at a low intensity will prepare your muscles for an increased level of activity. Gently stretch before you start to avoid a pulled muscle or muscle soreness.

End each session slowly, reducing your activity over 5 to 10 minutes. This will allow your heart rate to return to normal. While you are cooling down, you can also stretch. Hold each stretch for 20 to 30 seconds.

Always pay attention to what your body is telling you. If you feel faint or experience dizziness, a rapid heart beat, shortness of breath, or chest pain, stop exercising immediately and either sit up or lie down on your left or right side. Stop exercising if fluid leaks from your vagina or if you start having vaginal bleeding. In these situations, you should call your doctor. Additionally, it is not uncommon for women to experience some contractions during exercise; however, if these do not go away after 30 minutes, it is important to call your doctor.

Exercises That Are Recommended:

Aerobic activity that is recommended during pregnancy includes walking, biking, low-impact aerobics, and swimming. Exercise machines, such as ellipticals and StairMasters can be used safely during pregnancy. Dancing and hiking are also alternatives that many people enjoy safely during pregnancy. (See section of dancing during pregnancy.)

Exercises That Are Not Recommended

Avoid contact sports (boxing, wrestling, football, soccer, hockey), water skiing, snow skiing, and all forms of diving during pregnancy. Unless you are an expert equestrian, you should stop horseback riding because you could jar your body or be thrown from the horse. While some women have performed these activities successfully during pregnancy, that doesn't mean they were acting safely. Sports with a high risk of falls include gymnastics, skating, skiing, and hand gliding. These exercises greatly increase the chance of abdominal trauma. Wait until your baby is born and then resume these activities with your doctor's guidance. If at any point you experience abdominal trauma or injury, you should immediately call your doctor or go to the hospital for evaluation.

If you live at sea level or low altitudes and go to higher altitudes (6,000 feet and above), be sure to give yourself plenty of time (a few weeks) to adjust to the altitude before vigorous activity; there is far less oxygen at high altitude than at sea level, and your blood oxygen will be significantly reduced. If you live at a high altitude, your body has compensated by substantially increasing your blood hemoglobin, which correlates with oxygen delivery. If the hemoglobin level is increased by 30%, oxygen delivery will increase by 30%. Prepare for this situation by not rushing into vigorous exercise.

Elite and Professional Athletes

Despite your excellent physical conditioning, exercising at the same level during pregnancy may be risky. The results of studies on pregnant elite athletes are mixed, so it is important to be cautious.

One set of studies found no significant difference in maternal weight gain, fetal birth weight, or gestational ages in newborns of elite athletes compared to those who exercised more moderately. These self-reporting studies from two national physical fitness conferences involved women who exercised with heart rate intensities above 158 beats per minute or for 40 minutes or longer through the third trimester-or both.

However, many other reports have found that maximal exercise in professional athletes results in a slow fetal heart rate. Other studies have shown that women who exercise vigorously deliver babies with an average birth weight of as much as one pound less than babies born to women who exercise moderately. Sometimes these smaller babies have restricted growth.

If you are a professional or elite athlete, your doctor may want to monitor the growth of your fetus closely by measuring the growth of your uterus or by ultrasound. You may need to adjust your exercise to an appropriate level.