Physical activity before pregnancy and the risk of hypertensive disorders of pregnancy.

BACKGROUND

It is unclear whether prepregnancy physical activity influences the risk of hypertensive disorders of pregnancy and whether any impact is similar for preeclampsia and gestational hypertension.

OBJECTIVE

To evaluate the relation of prepregnancy physical activity with hypertensive disorders of pregnancy and its alignment with the current recommendations for physical activity for the general population.

STUDY DESIGN

We studied 28,147 singleton pregnancies from 18,283 women without chronic hypertension, cardiovascular disease, or cancer, participating in the Nurses' Health Study-II between 1989 and 2010. The women self-reported their physical activity before pregnancy and pregnancy complications, including preeclampsia and gestational hypertension. Logistic regression models using generalized estimating equations to account for within-woman correlations across pregnancies were used to estimate the relative risk (95% confidence interval) of preeclampsia and gestational hypertension across quartiles of prepregnancy physical activity, adjusting for age at pregnancy, parity, smoking, multivitamin use, infertility history, marital status, race, year of pregnancy, and history of preeclampsia.

RESULTS

We identified 842 (3.0%) pregnancies with preeclampsia and 905 (3.2%) pregnancies with gestational hypertension. Physical activity before pregnancy was related to a lower risk of hypertensive disorders of pregnancy (relative risk, 0.75 [95% confidence interval, 0.65-0.87] for women in the highest quartile compared with the lowest quartile). This relation was driven by a 39% lower risk of gestational hypertension (relative risk, 0.61; 95% confidence interval, 0.50-0.76) comparing women in the highest quartile of physical activity (≥30.6 metabolic equivalents of task-hours/week) vs women in the lowest quartile (<6.0 metabolic equivalents of task-hours/week). Women whose moderate physical activity levels exceeded those recommended in the Physical Activity Guidelines for Americans (>5 hours/week) had a 50% lower (relative risk, 0.50; 95% confidence interval, 0.36-0.69) risk of gestational hypertension than women who did not meet this recommendation (<2.5 hours/week). For vigorous physical activity, the risk of gestational hypertension was lower among the women who met (1.25-2.5 hours/week; relative risk, 0.77; 95% confidence interval, 0.64-0.93) or exceeded (>2.5 hours/week; relative risk, 0.76; 95% confidence interval, 0.62-0.92) the recommendations than women whose activity levels were below those recommended. Physical activity was not related to the risk of preeclampsia (relative risk, 0.93; 95% confidence interval, 0.76-1.14).

CONCLUSION

Physical activity before pregnancy may lower the risk of developing gestational hypertension but not preeclampsia.