Lead investigator Dr. Cuilin Zhang of the Harvard School of Public Health in Boston, explains that, “While smaller studies have suggested that exercise can reduce GDM risk, the current study is among the largest and best-designed that has examined this relationship to date. The study also looks at physical activity in greater detail, she added.

Dr. Zhang and her colleagues evaluated at 21,765 women participating in the Nurses Health Study II who had at least one singleton pregnancy between 1990 and 1998. A total of 1428 GDM cases were identified. The women had completed validated questionnaires assessing their level of physical activity and sedentary behavior.

After the researchers controlled for body mass index, diet and other potential confounding factors, they found that women in the highest quintile for vigorous physical activity were 23% less likely to develop GDM than those who were the least active.
Women who walked briskly but did not perform vigorous exercise were 34% less likely to develop GDM than those who walked at an easy pace, the researchers report in the March 13th issue of the Archives of Internal Medicine. Walking briskly for more than 30 minutes daily or climbing 15 flights of stairs every day also lowered GDM risk for women who did not exercise vigorously.

The researchers also found that women who watched at least 20 hours of television each week and did not exercise vigorously were 2.3 times more likely to develop GDM than active women who watched less than 2 hours of TV a week.