New research challenges the common belief that pregnant women need strenuous exercise to protect their health, suggesting that simply moving more and sitting less may make a remarkable difference.

Researchers from the University of Iowa have found that light physical activity throughout the day, combined with adequate sleep and reduced sedentary time, could lower the risk of developing serious pregnancy-related high blood pressure disorders by nearly 30%. The findings, published in the British Journal of Sports Medicine, come from one of the most detailed examinations yet of how women spend their time during pregnancy.

The study followed 470 pregnant women across all three trimesters. Participants in Iowa, Pittsburgh, and Morgantown wore movement monitors that tracked their activity around the clock, as well as separate devices that measured sleep. For at least a week during each trimester, researchers collected detailed information on how women walked, rested, and slept over a full 24-hour cycle.

The results point to what researchers describe as a “Goldilocks Day” — a balanced mix of movement and rest associated with the lowest risk of hypertensive disorders of pregnancy (HDP). These conditions include chronic hypertension, gestational hypertension and pre-eclampsia, all of which involve dangerously high blood pressure during pregnancy and can threaten the health of both mother and baby.

The recommended pattern includes less than eight hours of sedentary time daily, at least seven hours of light activity, about 22 minutes of moderate-to-vigorous activity such as brisk walking, and nearly nine hours of sleep each night.

Importantly, the study debunks a widespread myth that only vigorous exercise delivers meaningful benefits during pregnancy. Researchers observed that risk increased sharply among women who spent more than 10 hours each day sitting or lying down. Meanwhile, women who increased light activity to at least four hours daily saw their risk fall to around 15% from 30%.

“Just moving around more seems to have significant health benefits,” said Kara Whitaker, an associate professor in the Department of Health, Sport, and Human Physiology at the University of Iowa. “I think it may also be a more feasible target for women who are pregnant and not exercising regularly.”

Light activity includes simple actions many women already perform, such as walking casually, standing, doing household chores, or moving around the workplace. The findings may be especially important because these activities are easier to sustain than structured exercise programmes.

Researchers were surprised to discover that spending longer periods in moderate-to-vigorous exercise offered little additional benefit beyond roughly 22 minutes per day. Similarly, sleeping beyond the recommended duration produced no major extra advantages.

“We are identifying the optimal composition of movement behaviours across the day that is associated with the lowest risk of developing HDP and the most improved health outcomes,” Whitaker said. “This blueprint holds for each and every trimester of pregnancy.”

The findings are supported by a related study recently published in the Journal of the American Medical Association, which further examines the balance between sedentary behaviour and light activity. Together, the studies suggest that the small decisions women make throughout the day may matter more than previously understood.

The implications extend far beyond pregnancy. Previous clinical research has shown that women who develop hypertensive disorders during pregnancy are more than twice as likely to develop cardiovascular disease later in life. Heart disease remains the leading cause of death among women globally.

“We know that cardiovascular disease is the number one killer of women, and if we can intervene in pregnancy and prevent women from developing a hypertensive disorder of pregnancy, we are putting them on a better trajectory,” Whitaker said.

While the research was observational and does not prove direct cause and effect, it offers a practical message. For many pregnant women, better health may not begin with harder workouts. It may start with something much simpler: standing up, moving around and spending less time sitting still.