TOPLINE:

Pregnant individuals who sat for more than 10 hours daily faced a higher risk for adverse pregnancy outcomes than those who sat for around 7 hours daily. Conversely, engaging in very high patterns of light-intensity physical activity was associated with a reduced risk for adverse outcomes.

METHODOLOGY:

• Researchers analyzed data from a cohort study, including 470 pregnant adult volunteers (mean age, 30.7 years; 87.7% White) at less than 13 weeks of gestation from three states in the US to assess the link between light-intensity activities and the risk for adverse pregnancy outcomes.
• Participants wore an accelerometer on their thigh to track how much time they spent sitting, doing light activities, and walking, with activity patterns ranging from low to very high.
• Sedentary durations were calculated as the total time spent sitting or lying down, with average durations ranging from 7.3 h/d (low) to 11.8 h/d (very high); they were categorized into shorter bouts of less than 60 minutes and longer bouts of 60 minutes or more.
• Durations of light-intensity physical activity were calculated, ranging from low (3.0 h/d) to very high (7.3 h/d), and the activities were categorized into standing and ambulatory light-intensity activities.
• The composite outcome examined included hypertensive disorders of pregnancy, gestational diabetes, preterm birth, and small-for-gestational-age birth, which are linked to an increased maternal risk for cardiovascular events later in life.

TAKEAWAY:

• Patterns of high and very high sedentary behavior were associated with a higher risk for adverse pregnancy outcomes than patterns of low sedentary behavior (adjusted relative risk [aRR], 2.22; 95% CI, 1.12-4.43 and aRR, 2.19; 95% CI, 1.09-4.40, respectively).
• Patterns of very high light-intensity physical activity were associated with a lower risk for adverse pregnancy outcomes than patterns of low light-intensity physical activity (aRR, 0.52; 95% CI, 0.30-0.93).
• Participants with moderate (aRR, 0.76; 95% CI, 0.58-0.99) and high (aRR, 0.67; 95% CI, 0.49-0.92) daily step counts had a lower risk for adverse pregnancy outcomes than those with low step counts.

IN PRACTICE:

“Optimizing lighter-intensity activity patterns in pregnancy should be rigorously tested as a novel and practical strategy to improve pregnancy health outcomes,” the authors of the study wrote.

SOURCE:

The study was led by Bethany Barone Gibbs, PhD, West Virginia University, Morgantown, West Virginia. It was published online on May 27, 2026, in JAMA.

LIMITATIONS:

The observational study design made it hard to establish cause-and-effect relationships. The participants had limited diversity in terms of race, and most were healthy volunteers. There were only a few cases of gestational diabetes, preterm birth, and small for gestational age; therefore, the researchers could not assess how less sitting time and more light physical activity affected these outcomes separately.

DISCLOSURES:

The study was funded by the National Institutes of Health (NIH), 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. Some authors disclosed receiving grants from NIH or other sources during the conduct of the study and/or outside the submitted work.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.