Some activities pose increased risks in pregnancy and should be limited or avoided. These include:

• Scuba diving
• Activities that present an increased risk of falling (eg, skiing, skating)
• Sports with a high potential for contact (eg, ice hockey, soccer)
• Exercising at high altitudes (over 6,000 feet)
• Activity that involves lying flat on your back
• Resistance training with heavy weights

Exercising for 30 minutes a day on most days of the week is all that’s needed to maintain fitness and achieve related benefits. Women who wish to exercise for longer than 45 minutes should speak to their doctors before doing so. Getting your exercise in 10-minute spurts is also fine. As long as you exercise at a moderate or vigorous pace for at least 10 minutes, these short bursts of exercise can count toward your overall goal.

• Balance: As your body shape changes, so does your balance, which could put you at a greater risk of falling.
• Temperature regulation: Exercising in a controlled, air-conditioned environment will help keep temperature levels in check. And in general it’s a good idea to wear layers of clothes and exercise during the cooler hours of the day. Also, drink plenty of fluids to stay hydrated.
• Nutrition: Women who are pregnant need an extra 300 calories per day during the last six months of pregnancy. Exercising may further increase your calorie needs.

If you were sedentary before pregnancy, do not despair. You can still reap the benefits of exercise by gradually working up to 30 minutes per day. Realize that pregnancy is not the time for making significant gains in your fitness level—or for athletic competition. Competitive athletes who wish to maintain a more strenuous exercise schedule throughout pregnancy should do so only under the close supervision of their doctors.