30 minutes a day At least 150 minutes of moderate to vigorous exercise per week.  

That’s the official exercise prescription for all Americans, including pregnant women.

Current evidence shows little risk and big benefits of physical activity during normal pregnancy. Exercise may decrease complications (hypertension, gestational diabetes, preeclampsia) limit weight gain, improve mental state, increase fitness, and enhance weight loss postpartum.  Fetal benefits may include improved stress tolerance. 

Since 2002 ACOG* recommends pregnant women follow the physical activity guidelines for adults developed by the American College of Sports Medicine with the Centers for Disease Control and Prevention .  This is in alignment with the most recently published federal guideline, the 2008 US Physical Activity Guidelines for Americans. The Guidelines’ section on physical activity during pregnancy and the postpartum period encourages pregnant women to get as much physical activity as other adults, at least 150 minutes per week, or 30 minutes most days.

What’s moderate or vigorous exercise?  Moderate exercise noticeably increases your heart rate and breathing rate. You can talk, but you can’t sing. Moderate activity includes brisk walking, swimming, biking. Vigorous exercise makes you sweat and breathe heavily. It takes your heart rate up near maximum. You can talk only in short phrases. Vigorous activity includes running, swimming laps, biking more than 10 mph. Women who regularly engage in vigorous-intensity aerobic activity or high amounts of activity can continue their activity provided that their condition remains unchanged and they talk to their health care provider about their activity level throughout their pregnancy.  

Beware outdated cautions.  Many (more than half in some studies) of physicians still warn women to keep their heart rate below 140 while pregnant, or to avoid vigorous exercise. In one study 35% of obstetricians recommended against starting any exercise in the first trimester.  This misinformation is based on 1985 ACOG guidelines made in the absence of evidence and now superseded by strong urging to get moving.

Other evidence indicates one third to one half of physician prenatal care providers offer no advice on exercise during pregnancy. Those who do discuss physical activity report spending a total of 5 to10 minutes on the topic.

Lack of information, or misinformation, may explain in part why only 57% of pregnant women in the U.S. reported they got any moderate to vigorous leisure activity and only 54% did any moderate household activity. Despite beliefs in the health benefits of exercise for both themselves and their babies, most women are not engaging in exercise at the recommended levels. Women who demonstrated good understanding of exercise during pregnancy were no more likely to exercise than their less informed counterparts.

Beginnings Pregnancy Guide recommends a combination of aerobic, conditioning and stretching exercise. 

The Exercise Guide for Moms-to-be (p 27) adheres to current national guidelines with one change. 

It now says:  Exercise 30 minutes at least 3 times a week. More is better.                      The 2011 revision will say:  Exercise 30 minutes at least 5 times a week. More is better.