Influence of exercise type on maternal blood pressure adaptation throughout pregnancy.

Background: It has been reported that 10% of all pregnancies are complicated by a hypertensive disorder of pregnancy. Previous research has shown that moderate-vigorous intensity exercise has a positive effect on maternal resting blood pressure. A research gap, however, exists related to how different types of exercise (resistance, aerobic, combined resistance and aerobic) affect maternal blood pressure. Most of the previous studies solely focused on aerobic exercise.

Objective: The aim of this study was to examine the effects of exercise types on maternal blood pressure throughout pregnancy.

Study Design: This study employed a secondary analysis using data from a randomized controlled prenatal exercise intervention trial This study utilized 3 exercise intervention groups (aerobic, resistance, combination) and compared the results with those of a nonexercize control group. Participants completed 3 50-minute sessions weekly from 16 weeks of gestation until delivery. Maternal vital signs and physical measurements such as systolic blood pressure, diastolic blood pressure, and heart rate were measured every 4 weeks throughout the intervention period. Between-group mean differences in maternal measurements were assessed using Pearson's chi-square tests for continuous (age, prepregnancy body mass index, heart rate, systolic blood pressure, diastolic blood pressure, pulse pressure) variables. For gravida, exact Wilcox 2-sample tests were performed to determine between-group differences in mean values. Hierarchical linear growth curves were used to estimate maternal trajectories of systolic blood pressure and diastolic blood pressure from 16 weeks to 36 weeks' gestation in each of the 4 groups (aerobic, combination, control, and resistance).

Results: There were no differences among the groups in maternal age or prepregnancy body mass index. Controlling for maternal body mass index, the lowest significant systolic blood pressure curve was noted throughout the pregnancy for women who participated in resistance exercise, followed by women in the aerobic exercise group all relative to the no exercise control group. At 36 weeks' gestation, the systolic blood pressure was lower in the resistance group by 12.17 mm Hg (<.001) and in the aerobic group by 7.90 mm Hg (<.001) relative to controls. No significant change in systolic blood pressure was noted in the combination group in comparison with controls at 36 weeks' gestation. Similarly, we demonstrated a significantly lower linear growth curve in diastolic blood pressure that was maintained throughout pregnancy in any exercise type relative to controls. After controlling for maternal body mass index, all 3 exercise types (combination, resistance, and aerobic) significantly predicted a similar decrease in diastolic blood pressure that was maintained throughout pregnancy. At 36 weeks' gestation, the diastolic blood pressure was lower in the aerobic group by 7.30 mm Hg (<.01), in the combination group by 6.43 mm Hg (<.05), and in the resistance group relative to controls.

Conclusion: Overall, all exercise types were beneficial in lowering maternal resting blood pressure throughout pregnancy. Resistance training was noted to be the most beneficial in improving systolic blood pressure, followed by aerobic exercise. All 3 exercise groups were noted to improve diastolic blood pressure equally. Further research needs to be done to determine if either resistance or aerobic exercise throughout pregnancy decreases the risk for hypertensive disorders of pregnancy and the associated morbidity and mortality.