Pregnant women who limit sedentary time to no more than eight hours daily and increase light physical activity to at least seven hours daily may reduce their risk of developing hypertensive disorders by nearly 30%, according to preliminary research presented at the American Heart Association's EPI|Lifestyle Scientific Sessions 2026. The study of 470 women found that sedentary behaviors and light physical activity were the strongest predictors of hypertensive disorder risk across all trimesters.
The research measured 24-hour activity patterns across a 7-day period during each trimester using wearable monitors. The lowest-risk daily pattern identified 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 typical daily patterns. When compared to the least healthy movement patterns measured, the optimal activity combination reduced risk by nearly 80%.
"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."
The risk of hypertensive disorders rose for women who sat more than 10 hours daily or had less than five hours of light activity. High blood pressure develops in up to 10% of all pregnancies and is the leading cause of fetal and maternal disease and death. According to the American Heart Association, high blood pressure during pregnancy is associated with increased future cardiovascular disease risk. The study results align with the American Heart Association's Life Essential 8 for Pregnancy recommendations, which encourage women to find ways to move throughout the day.
"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." The study included women from three healthcare centers in Iowa, Pennsylvania and West Virginia who were followed from their first trimester until six weeks after delivery.
Natalie A. Bello, M.D., M.P.H., an American Heart Association volunteer expert not involved with the study, noted that "the researchers extend this to the pregnant population where nearly 20% of participants developed a hypertensive disorder of pregnancy. They saw incremental associations between more physical activity and lower risk of developing preeclampsia or gestational hypertension." The study authors note that research with more participants from diverse population groups is needed to confirm the findings, as most participants were non-Hispanic white with higher education and income levels.
