Pregnant women may reduce key health risk through more light exercise, study finds

Light exercise and less sitting may reduce pregnant women’s risk of serious blood pressure complications, according to a new study.

Researchers have proposed a daily activity and sleep guide that they say was linked to a nearly 30 per cent lower risk of hypertensive disorders of pregnancy.

The suggested pattern includes fewer than eight hours of sedentary time, at least seven hours of light physical activity, around 22 minutes of more intense activity and nearly nine hours of sleep.

The University of Iowa-led study examined the daily behaviours of 470 pregnant women across all stages of pregnancy.

Participants wore monitors that measured physical activity over 24-hour periods and recorded how long they spent asleep.

Hypertensive disorders of pregnancy include chronic high blood pressure, gestational hypertension and pre-eclampsia.

Gestational hypertension is high blood pressure that develops during pregnancy, while pre-eclampsia is a potentially serious condition involving high blood pressure and signs that organs may be affected.

Sedentary behaviour means being mostly inactive, such as sitting or lying down.

Light physical activity can include casual walking, moving around the home or standing.

Moderate to vigorous activity includes movement such as brisk walking, where breathing and heart rate increase.

Kara Whitaker, associate professor in the department of health, sport, and human physiology at Iowa and corresponding author of the study, said: “We are identifying the optimal composition of movement behaviours across the day associated with the lowest risk of developing HDP and the most improved health outcomes.

“This blueprint holds for each and every trimester of pregnancy.”

Study participants were enrolled at sites in Iowa City, Pittsburgh and Morgantown, West Virginia.

The women wore activity and sleep monitors for at least one week during each trimester of pregnancy.

Four in five participants were non-Hispanic white and nearly a quarter lived in rural areas.

The data showed a steep rise in risk among pregnant women who were sedentary for more than 10 hours a day.

Women who increased light physical activity to at least four hours a day reduced their risk of hypertensive disorders of pregnancy to 15 per cent from 30 per cent.

Whitaker said: “Just moving around more seems to have significant health benefits.

“And I think it also may be a more feasible target for women who are pregnant who are not exercising regularly.”

The researchers said they were surprised that longer durations of moderate to vigorous physical activity did not appear to provide additional benefit.

Sleep beyond a certain duration also did not appear to bring major further benefits.

Whitaker said: “Through this study, we are providing evidence that reducing sedentary behaviour and engaging in light physical activity are important, and maybe more important, when it comes to pregnancy and health.”

The findings may be relevant beyond pregnancy because clinical research has shown that women who develop hypertensive disorders of pregnancy are more than twice as likely to develop heart disease later in life.

Cardiovascular disease includes conditions affecting the heart and blood vessels, such as heart disease and stroke.

Whitaker said: “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, away from cardiovascular disease and toward more optimal cardiovascular health.”

The study was published online on June 10.

A second study, published online on May 27, looked more closely at the ratio and type of sedentary behaviour and light physical activity linked to a lower risk of hypertensive disorders of pregnancy.

Whitaker is a lead co-author on that study.

Co-authors in the June 10 study include Alex Crisp, Jaemyung Kim, Karina Smith, Donna Santillan, Mark Santillan and Bridget Zimmerman, from Iowa; Jacob Gallagher, from Iowa State University; Melissa Jones, from Oakland University in Michigan; Bethany Barone Gibbs, Katrina Wilhite, Alexis Thrower and Iqra Sheikh, from West Virginia University; and Sabera Rahman, Janet Catov, Christopher Kline and Maisa Feghali, from the University of Pittsburgh.

The National Institutes of Health, the University of Iowa Institute for Clinical and Translational Science, the University of Pittsburgh Clinical and Translational Science Institute and the West Virginia Clinical and Translational Science Institute funded the research.