A: Your doctor gave you good advice, as exercise has many benefits during pregnancy. In addition to increased energy, flexibility and endurance, many women find that exercise improves their mood as well. Additional benefits include improved regulation of your blood sugar and prevention of backache. Finally, exercise during pregnancy is good preparation for childbirth, which is a physically demanding endeavor, too.

If you haven’t exercised before, it’s important to start slowly and choose activities that appeal to you. Exercise should be fun. Avoid unduly strenuous activities or playing “weekend warrior.” It’s better to exercise a little bit each day rather than overexerting yourself on weekends.

Begin with a simple warm-up such as walking. Try gentle stretches that can release tension from your neck, back and extremities. If you join a health club or YMCA, you can learn how to use some of the exercise machines. Stationary walking, biking and the elliptical trainer are good choices.

However, it may be more fun to join a class, especially if you have the option of exercising with other moms-to-be. Prenatal yoga, low-impact aerobics and prenatal water aerobics are all excellent during pregnancy.

Remember, there is no need to feel competitive with your classmates. If you feel out of breath, fatigued, or if you experience pain, discontinue your activity until you feel better. You should also stop if you notice regular uterine contractions or have vaginal bleeding. And as you finish exercising, include a cool-down period. In general, you should avoid overheating and stay well hydrated. This means drinking water before, during and after you exercise and not overdressing.

Other pregnancy exercise tips: wear a supportive bra, consider wearing an abdominal support if you find that exercising with a big belly strains your back and avoid lying flat on your back for a sustained amount of time. The weight of your uterus can compress the large vein that leads to your hearts (the inferior vena cava) and cause you to feel lightheaded.

For additional advice on exercise, read my article on this website entitled “Exercise and Pregnancy.”