Causal effects of physical activity and sedentary behaviors on hypertensive disorders of pregnancy: a two-sample Mendelian randomization study

Background Hypertensive disorders of pregnancy (HDPs) are major causes of maternal and perinatal morbidity. While observational studies suggest physical activity may reduce HDP risk, confounding and reverse causality limit causal inference.Methods We conducted a two-sample Mendelian randomization study using genetic instruments for 11 activity traits from UK Biobank and outcome data for gestational hypertension and pre-eclampsia from FinnGen.Results Light do-it-yourself (DIY) activities were associated with lower risks of gestational hypertension (β(logOR) (logOR) (logOR) = −3.56, P = 0.002) and pre-eclampsia (β = −3.54, P = 0.029). Aerobic exercise was associated with lower pre-eclampsia risk (β = −3.56, P = 0.017). No significant associations were found for vigorous activity, moderate-to-vigorous activity, or the three specific sedentary behaviors examined (time spent using a computer, time spent watching television, and time spent driving).Conclusion This study provides causal evidence that specific physical activities confer protection against HDPs. Genetically predicted light DIY activities were associated with lower risks of both gestational hypertension and pre-eclampsia, while aerobic exercise was associated with lower pre-eclampsia risk. The three sedentary behaviors examined showed no causal associations. These findings highlight light-intensity domestic activities and aerobic exercise as accessible strategies for HDP prevention in prenatal care.