Fewer Limits, More Favor for Exercise in Pregnancy


NEW YORK — What physicians and researchers know for sure about physical activity during pregnancy hasn't changed much since the early 1900s, James M. Pivarnik, Ph.D., said at the annual meeting of the Diabetes in Pregnancy Study Group of North America.

Recommendations from the Handbook for Prospective Mothers, published in 1913, advised pregnant women that the amount of exercise needed cannot be precisely stated, walking is the best kind of exercise, and all kinds of violent exertion should be avoided. Although today's recommendations have been more thoroughly researched, they don't provide women with many more definitive answers, said Dr. Pivarnik, director of the Center for Physical Activity and Health at Michigan State University, East Lansing.

But professional medical societies are generally becoming less conservative in their recommendations about exercise for pregnant women. For example, the American College of Obstetricians and Gynecologists has revised its recommendations three times in the last 2 decades and has moved away from strict limits on physical activity.

In 1985, ACOG released its first exercise guidelines for pregnant women, which included time limits for exercise and recommended that a woman's heart rate not exceed 140 beats per minute. However, even these early guidelines included the disclaimer that physically fit pregnant woman may tolerate a more strenuous program.

“There was actually the dispensation way back then but a lot of people just didn't follow that,” Dr. Pivarnik said.

In 1994, ACOG issued updated guidelines that were less cautious and emphasized the benefits of mild to moderate exercise at least 3 days a week. “There was more stress on the health benefits, rather than the fear,” he said.

The most recent ACOG guidelines on exercise in pregnancy were issued in 2002 and address activity among recreational and competitive athletes. Specifically, the guidelines recommend that athletes with uncomplicated pregnancies can remain active during pregnancy and should modify their routines as medically indicated. However, since information on strenuous exercise is limited, these women require close medical supervision.

And most pregnant women without medical or obstetric complications can aim to engage in 30 minutes or more of moderate exercise a day, according to the guidelines.

Guidelines issued in Canada in 2003 by the Society of Obstetricians and Gynaecologists of Canada and the Canadian Society for Exercise Physiology take an even more aggressive approach. The joint 2003 guidelines recommend that all women without contraindications should be encouraged to participate in aerobic and strength-conditioning exercises during pregnancy.

But some physicians and nurse-midwives who deal with obstetrics are not up to date on the guidelines and still recommend more conservative approaches, such as not exceeding a heart rate of 140 beats per minute, Dr. Pivarnik said. “There's no evidence that that's the way it should be done,” he said.

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