BOSTON - Pregnant women may significantly reduce their risk of developing hypertensive disorders such as gestational hypertension and preeclampsia by limiting sedentary time to no more than eight hours a day and increasing light physical activity to at least seven hours daily, according to preliminary research presented at the American Heart Association’s EPI|Lifestyle Scientific Sessions 2026. The study, which followed nearly 500 women across three U.S. cities from 2020 to 2025, measured sedentary behavior, sleep and physical activity over 24 hours for seven consecutive days during each trimester.
The findings indicate that the balance of sitting time and light intensity movement throughout the day may be more critical than previously thought. “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. “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.”
High blood pressure develops in up to 5%-10% of all pregnancies and is the leading cause of fetal and maternal disease and death. The study included 470 women aged 18 to 45, 83% non-Hispanic white, enrolled from 2021 to 2024 at health care centers in Iowa, Pennsylvania and West Virginia. Participants wore two monitors to measure activity and sleep, and medical records were used to track hypertensive disorders. Of the participants, 18.6% developed hypertensive disorders of pregnancy.
The optimal daily pattern associated with the lowest risk 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 typical movement patterns, this optimal combination reduced risk by more than half, and by nearly 80% compared to the least healthy patterns. Risk increased for those sitting more than 10 hours per day or engaging in less than five hours of light activity.
The study aligns with the American Heart Association’s Life Essential 8 for Pregnancy recommendations, which encourage moving throughout the day, adequate sleep and healthy eating. “These findings have the potential to shift how we think about physical activity and sleep during pregnancy,” Whitaker said. “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 in the future.”
Natalie A. Bello, M.D., M.P.H., an American Heart Association volunteer expert, noted that while the association between physical activity and lower risk is promising, further studies are needed to establish causality. The study had limitations, including a predominantly white, higher-education and income sample, and the inability to separately analyze preeclampsia and gestational hypertension due to small case numbers. Researchers call for more diverse studies to confirm these findings and inform future guidelines.
