Effect of exercise on blood pressure in pregnant women with a high risk of gestational hypertensive disorders.

Objective: To prospectively determine whether moderate exercise during pregnancy lowers blood pressure.
Study Design: A randomized, controlled trial with one test group and one control group. All subjects have a history of mild hypertension, gestational hypertensive disorders or a family history of hypertensive disorders. Subjects were recruited before 14 weeks' gestation. After four weeks of observation, the subjects were randomly assigned to either the exercise or control group. The exercise group visited the laboratory three times a week for 10 weeks (18-28 gestation weeks) to perform 30 minutes of exercise at Rating of Perceived Exertion level 13.
Results: A total of 16 pregnant women (mean age, 30 years) participated. The mean metabolic equivalent during exercise sessions was 4.7 (SD = 0.8). Blood pressure measurements were compared before and after the 10-week exercise period in the two groups. Systolic blood pressures did not change significantly, but diastolic blood pressure (DBP) in the exercise group decreased by 3.5 mm Hg, while that in the control group increased by 1.1 mm Hg. Thus, the pre-post change in DBP differed by 4.6 mm Hg between groups. Exercise treatment reduced the diastolic blood pressure to a near-significant level in the exercise group (t = 2.34, df = 7, P = .052). Percent body fat did not differ between the exercise and control groups either before or after exercise treatment. ANOVA revealed that pregnancy had a significant effect (F(1, 14) = 5.7, P = .03) on increasing the percentage of fat, but exercise treatment did not (F(1, 14) = .18, P = .68). Estimated energy expenditure in overall daily physical activities during the intervention did not differ between the two groups despite the inclusion of exercise.
Conclusion: This study detected a strong trend that 10 weeks of moderate exercise lowered the diastolic blood pressure among pregnant women at risk of hypertensive disorders. The reductions were probably due to the effect of exercise itself, not to weight or overall daily physical activity levels.