Greater standing, light movement, and increased daily steps during pregnancy may be associated with healthier outcomes for mothers and babies, according to a study published in JAMA on July 21.
The research followed 470 pregnant women from less than 13 weeks gestation through the end of their pregnancies. Device-based monitoring was used each trimester to assess sedentary behavior, light-intensity physical activity, and daily steps. Medical records were reviewed for adverse pregnancy outcomes such as hypertensive disorders of pregnancy, gestational diabetes, preterm birth, and infants who were small for gestational age.
The study found that about 37% of participants experienced an adverse pregnancy outcome. Participants averaged 10 hours per day sitting, 4.6 hours per day in light-intensity physical activity, and took an average of 6,783 steps daily. Moderate-to-vigorous-intensity physical activity was performed for a median of about 153 minutes weekly.
Women who sat longer—averaging over ten hours per day—had more than twice the risk of adverse outcomes compared to those averaging just over seven hours sitting per day. In contrast, those engaging in higher amounts of light-intensity physical activity or taking more daily steps had lower risks: seven hours per day of light-intensity activity was linked with half the risk compared to three hours per day; moderate (around 6,000) or high (around 8,500) step counts were also associated with lower risks compared to low step patterns (about 4,000).
A key strength cited by researchers is the use of thigh-worn accelerometers capable of distinguishing between seated and standing stationary behavior—a methodological advantage over wrist- or waist-worn devices. The findings suggest that breaking up prolonged sitting periods with increased standing or low-intensity movement may reduce risks related to hypertensive disorders during pregnancy.
However, the authors note limitations, including the observational design—which cannot determine causality—and limited racial and ethnic diversity among participants. They recommend further studies involving larger samples representing broader populations as well as higher-risk pregnancies.
