Babies born to mothers with GDM may be large at birth and suffer complications such as jaundice. These children are more likely to become obese and develop diabetes in early adulthood. Women with GDM are at increased risk of developing other complications during pregnancy, such as preeclampsia, and they are more likely to develop type 2 diabetes after pregnancy.

The results of this new study suggest that women who are physically active during the year before and/or during early pregnancy may be less likely to develop GDM.

The study, which was funded by The National Institute of Child Health and Human Development at National Institutes of Health, suggests that current efforts to encourage Americans to engage in more frequent physical activity may also benefit pregnant women and result in substantial reductions in the incidence of GDM.

Lead author Jennifer Dempsey and colleagues report that women who participated in recreational physical activity during the year before pregnancy reduced their risk of GDM by 56 percent. During this time period, women who exercised for about four hours per week were 76 percent less likely to develop GDM when compared with women who did not exercise. In addition, women who participated in recreational physical activity both before and during early pregnancy enjoyed a 69 percent reduction in risk.

The study, which is ongoing at Swedish Medical Center in Seattle and led by Drs. Michelle Williams, Tanya Sorensen and David Luthy, was presented this morning at the 24th annual meeting of the Society for Maternal-Fetal Medicine in New Orleans and will be published later this year in the American Journal of Epidemiology.

The investigators are currently conducting additional analyses to determine which metabolic or physiological changes associated with exercise may contribute to this reduced risk of GDM. They are also conducting studies to help identify which specific types, intensities and duration of exercise are associated with optimal pregnancy outcomes.