BOSTON – Pregnant women who limit their sedentary time to no more than eight hours a day and increase light physical activity to at least seven hours daily may reduce their risk of developing hypertensive disorders of pregnancy by nearly 30%, according to preliminary research presented at the American Heart Association’s EPI|Lifestyle Scientific Sessions 2026.
The study, which included 470 pregnant women across three U.S. cities from 2021 to 2024, measured sedentary behavior, sleep and physical activity across a 7-day, 24-hour timeframe during each trimester. The amount of time spent sitting and doing light physical activity were found to be the main predictors of developing blood pressure-related conditions such as gestational hypertension and preeclampsia.
“Our study suggests that in the real world, where daily routines vary widely, it may actually be the balance of sitting time and light intensity movement across the entire day that matters most,” said lead study author Kara Whitaker, Ph.D., M.P.H., FAHA, an associate professor at the University of Iowa in Iowa City. “This doesn’t mean exercise isn’t beneficial – rather, that when it comes to hypertensive disorders of pregnancy, everyday movement and limiting long periods of sitting may play a bigger role than we previously understood.”
According to the American Heart Association, high blood pressure during pregnancy and other adverse pregnancy conditions are associated with an increased risk of future cardiovascular disease. Hypertensive disorders of pregnancy affect 5% to 10% of pregnancies and are a leading cause of fetal and maternal disease and death.
The study found that among participants, 18.6% developed hypertensive disorders of pregnancy. The lowest-risk daily pattern included about six hours of sitting, nearly eight hours of light physical activity, four minutes of higher-intensity activity and roughly 10 hours of rest. This pattern was linked to an 8% chance of developing hypertensive disorders, compared to 16.9% among those with a typical daily pattern. Compared to the least healthy patterns, the optimal combination reduced risk by nearly 80%.
Sedentary behaviors and light physical activity were the strongest predictors of risk across all trimesters. The risk rose for those who sat more than 10 hours per day or had less than five hours of light activity daily.
Natalie A. Bello, M.D., M.P.H., an American Heart Association volunteer expert, noted that the findings extend known benefits of physical activity to pregnant populations. “The researchers saw incremental associations between more physical activity and lower risk of developing preeclampsia or gestational hypertension,” she said. “It remains to be seen whether this association is causal, and future studies designed to increase physical activity and reduce sedentary behavior in pregnancy are needed.”
The study results align with the American Heart Association’s Life’s Essential 8 for Pregnancy recommendations, which encourage moving throughout the day, adequate sleep, healthy eating and blood pressure monitoring.
Whitaker emphasized that these findings could shape future guidelines. “Right now, there are no clear, quantitative guidelines for how much sitting or light intensity movement is healthiest during pregnancy, and our results provide early evidence that could help shape those recommendations.”
Study limitations include a predominantly white, higher-educated participant group, which may not reflect other populations. The researchers call for larger, more diverse studies to confirm findings and explore specific relationships between activity patterns and different hypertensive disorders.
