Guidelines urge physical activity during pregnancy

Moderate physical activity during pregnancy does not contribute to low birth weight, premature birth or miscarriage and may actually reduce the risk of complications, according to a Michigan State University professor who contributed to the U.S. government's first-ever guidelines on physical activity.

Kinesiology professor James Pivarnik and doctoral students Lanay Mudd and Erin Kuffel wrote the section on pregnancy and postpartum activity as part of the 2008 Physical Activity Guidelines unveiled Oct. 7 in Washington, D.C., by the Department of Health and Human Services. Pivarnik, president-elect of the American College of Sports Medicine, attended the event and spoke on behalf of the organization and MSU.

"There has been quite a dramatic change in regards to pregnancy and exercise," said Pivarnik, who has studied the topic for more than 20 years. "While it used to be thought that avoiding exercise meant avoiding harm to the fetus, research now shows physical activity can not only improve health of the mother but also provide potential long-term benefits for the child."

Specifically, the guidelines call for women to get at least 150 minutes of moderate-intensity aerobic activity per week during pregnancy and the postpartum period, preferably spread throughout the week. In addition to health benefits, moderate physical activity also may reduce the length of labor, evidence suggests. The guidelines call for women to avoid doing activities that involve lying on their back after the first trimester and activities with high risk of falling or abdominal trauma.

During the postpartum period, regular physical activity continues to benefit a woman's overall health, according to Pivarnik's research, by increasing her cardiorespiratory fitness and improving her mood. Physical activity after pregnancy also helps women achieve and maintain a healthy weight, and when combined with appropriate caloric restriction, promotes weight loss.

"In the time I have been performing research on exercise during pregnancy, we have shifted from cautious conservatism to the current guidelines, which encourage women to be active throughout gestation," Pivarnik said.

Also as part of the new guidelines, the government recommends 150 minutes of activity for adults per week. The move toward measuring recommended exercise by overall minutes as opposed to specific time and frequency requirements mirrors research recently published by Mudd, Pivarnik, Mathew Reeves from MSU's Department of Epidemiology, and Ann Rafferty from the Michigan Department of Community Health.

That study, published this month in the journal Medicine and Science in Sports and Exercise, used a broader approach toward calculating compliance with exercise requirements and found when measured by the amount of energy expended, the number of respondents who met guidelines was significantly higher.

"We found that by following the letter of the law many people who may be getting enough physical activity were not being counted," Mudd said. "But we still have a majority of people who are inactive or are not active enough.

"The new guidelines can help shape people's behaviors and get them on the right track to being healthy," she added. "They allow individuals more flexibility in how and when to perform their activities."

October 9, 2008