Pregnant women may significantly reduce their risk of developing hypertensive disorders such as gestational hypertension and preeclampsia by limiting sitting 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 in Boston.
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. Women who limited sedentary time to about eight hours a day, engaged in at least seven hours of light physical activity, and averaged 22 minutes of higher-intensity activity and nine hours of sleep daily had a 30% lower risk of developing hypertensive disorders of pregnancy.
"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."
Hypertensive disorders of pregnancy affect up to 5%-10% of pregnancies and are a leading cause of fetal and maternal disease and death. According to the American Heart Association, high blood pressure during pregnancy is linked to increased future cardiovascular disease risk.
The study found that sedentary behaviors and light physical activity were the strongest predictors of hypertensive disorders across all trimesters. The lowest-risk daily pattern included about six hours of sitting, nearly eight hours of light activity, four minutes of higher-intensity activity, and roughly 10 hours of rest, associated with an 8% chance of developing hypertensive disorders compared to 16.9% for typical patterns. Risk rose for those sitting more than 10 hours per day or with less than five hours of light activity.
"These findings have the potential to shift how we think about physical activity and sleep during pregnancy," said Whitaker. "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."
The results align with the American Heart Association's Life Essential 8 for Pregnancy recommendations, which encourage movement throughout the day, adequate sleep, and healthy eating.
Natalie A. Bello, M.D., M.P.H., an American Heart Association volunteer expert not involved in 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. 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."
Study limitations include a predominantly white, higher-education cohort, so results may not generalize to other populations. Additionally, due to small case numbers, the researchers could not analyze preeclampsia and gestational hypertension separately.
More research is needed to confirm whether helping pregnant women sit less and move more can reduce hypertensive disorder risk. The findings are considered preliminary until published in a peer-reviewed journal.
