ANN ARBOR—A new study by a University of Michigan School of Nursing professor shows that moderate exercise during pregnancy can lower blood pressure and reduce the risk of developing gestational hypertension, a disease that affects as many as 12 percent of women.

In a pilot study of 16 high-risk women, SeonAe Yeo, a University of Michigan associate professor of nursing, concluded that moderate exercise lowered diastolic blood pressure in their pregnancies by as much as 4.6 millimeters of mercury, or mm Hg. The results indicate that moderate exercise may contribute to the prevention of gestational hypertension or at least reduce the risk in pregnant women.

“Because this is a small sample size, the drop in blood pressure may not seem significant, but in reality, it is. Once we’ve launched our follow-up study, we expect to see a much more significant drop,” said Yeo, senior author of the study that appears in the April edition of The Journal of Reproductive Medicine.

The randomized, controlled trial focused on 16 women with a history of mild hypertension, gestational hypertensive disorders or a family history of hypertensive disorders. The women, who were on average 30 years old, were recruited at 14 weeks gestation. Prior to the study, the women were either sedentary or exercised very little. Some were assigned to an exercise group, while others kept their usual level of activity to provide a comparison, or control group.

Those assigned to the exercise group engaged in treadmill or bicycle exercise three days a week at 30-minute intervals for 10 weeks. The women had similar body compositions and were in the same weight range, giving the researchers a consistent group for determining whether exercise could reduce blood pressure.

While the exercise group experienced a decline in diastolic blood pressure, the control group did not experience significant changes. The diastolic blood pressure for the women in the control group changed from an average of 65.9 mm Hg to 67.0 mm Hg after the 10-week trial. The diastolic blood pressure for the women in the exercise group changed from an average of 64.0 mm Hg to 60.5 mm Hg after 10 weeks.

“We concluded that blood pressure change is probably due to exercise, not to body composition difference or overall daily physical activity level,” Yeo said.

During the first trimester of pregnancy, blood pressure in general tends to drop—in some cases by as much as 10 percent. In the second and third trimester, it generally returns to its normal level.

Preeclampsia, which is high blood pressure, typically accompanied by swelling called edema and protein in the urine, or proteinuria, affects 5 to 7 percent of all women and 25 percent of high risk women.

Exercise can have an unrefutable impact on health. It has been proven to reduce lipoprotein levels (fat and protein content in the arteries) and resting blood pressure (diastolic blood pressure). It also benefits mental well being and carbohydrate tolerance (the ability to process sugars).

Credentials for SeonAe Yeo are as follows: R.N., M.S., M.S.N., Ph.D.

This study was funded by a grant from Blue Cross/Blue Shield of Michigan Foundation.

Facts about pregnancy and exercise:

•Regular exercise during pregnancy improves labor and delivery processes and birth outcomes.• Women who engage in regular exercise experience easier labor and tend to have their infants on time.• Women who exercise regularly during pregnancy tend to have heavier infants than those who do not.• Exercise during pregnancy also seems to reduce pregnancy-related discomfort, such as nausea and fatigue.

School of NursingSeonAe YeoThe Journal of Reproductive MedicineBlue Cross/Blue Shield of Michigan Foundation