Pregnant women who spent more than 10 hours a day sedentary had a sharply higher predicted risk of developing hypertensive disorders of pregnancy, according to new research that tracked movement and sleep throughout all three trimesters.
New research found that pregnant women who spent more than about 10 hours a day sedentary had a higher predicted risk of gestational hypertension or preeclampsia, although the study does not establish causation.
The finding does not mean sitting for 10 hours causes preeclampsia, nor does it show that simply standing up more often will prevent high blood pressure during pregnancy. But the study adds an important piece to previous research, which has generally found benefits from exercise during pregnancy while producing much less consistent evidence about prolonged sedentary time.
The new results suggest that ordinary light movement, not just planned workouts, could be an important part of the picture.
Key Takeaways
- Researchers analyzed 470 pregnant participants and objectively measured movement and sleep during each trimester.
- 86 participants, or 18.3%, developed a hypertensive disorder of pregnancy.
- Predicted risk increased particularly steeply when sedentary time exceeded about 10 hours per day.
- Lower amounts of light physical activity were also associated with greater predicted risk.
- The findings do not establish that prolonged sitting causes gestational hypertension or preeclampsia.
- Earlier research strongly supports appropriate physical activity during pregnancy, but evidence specifically linking sedentary behavior with pregnancy-related hypertension has been less consistent.
Researchers Tracked the Entire 24-Hour Day
Rather than looking only at whether pregnant women exercised, Whitaker et al. (2026) examined how participants divided an entire day among sedentary behavior, light physical activity, moderate-to-vigorous physical activity and sleep.
The Pregnancy 24/7 cohort enrolled 500 participants between 2021 and 2024 at three sites in the United States. The final analysis included 470 participants who contributed data from at least one trimester.
Participants wore movement monitors for seven days during each trimester, at approximately 10 to 12 weeks, 20 to 22 weeks and 32 to 34 weeks of pregnancy. Researchers used an activPAL3 micro monitor to measure sedentary behavior and physical activity, while an Actiwatch Spectrum Plus was used to assess sleep.
This is an important strength of the research. Instead of relying mainly on participants remembering how long they spent sitting or exercising, the investigators repeatedly measured movement throughout pregnancy.
Hypertensive disorders were identified from medical records and included gestational hypertension and preeclampsia.
Among the 470 participants, 86, or 18.3%, developed a hypertensive disorder of pregnancy. Gestational hypertension occurred in 57 participants, preeclampsia in 28 and superimposed preeclampsia in one.
Risk Increased as Sedentary Time Became Very High
The relationship between sitting and hypertension risk was not simply a straight line.
The researchers found that predicted risk increased particularly steeply when sedentary behavior exceeded approximately 10 hours per day.
Light physical activity showed the opposite pattern. The largest differences appeared when people moved from very low amounts of light activity, around one to two hours per day, toward roughly four to five hours per day.
The researchers also modeled what might happen when time was redistributed between sedentary behavior and light activity while moderate-to-vigorous activity and sleep were kept constant.
A reference daily pattern containing approximately 9.6 hours of sedentary behavior and 5.1 hours of light activity corresponded to a predicted hypertensive-disorder risk of 15.4%.
At the lower-risk end of the modeled range, approximately 5.7 hours of sedentary time and 9 hours of light activity corresponded to a predicted risk of 8.4%.
At the other extreme, approximately 13.5 sedentary hours and 1.25 hours of light activity corresponded to a predicted risk of 33.6%.
These figures should not be interpreted as recommended daily schedules. They came from statistical modeling of an observational cohort. Pregnant women were not randomly assigned to spend six, 10 or 13 hours sitting each day.
The 10-hour figure should therefore not be treated as a precise biological cutoff where sitting suddenly becomes dangerous.
Ordinary Movement May Matter Alongside Exercise
One of the most interesting aspects of the study is that the signal was not limited to moderate or vigorous exercise.
Light physical activity can include relatively easy movement performed throughout everyday life. In the study’s analysis, standing was also included within the light-activity category.
When moderate-to-vigorous activity and sleep were held constant, replacing sedentary time with light activity was associated with lower predicted risk.
That does not establish that light activity is more beneficial than exercise. Nor does it mean pregnant women should replace recommended exercise with standing or slow movement.
Instead, the findings suggest that focusing only on workouts may overlook what happens during the rest of the day.
A person can complete a daily workout while still spending many of the remaining waking hours sitting. The Pregnancy 24/7 results raise the possibility that this broader daily pattern may also matter for pregnancy-related hypertension.
Previous Research on Sitting During Pregnancy Was Inconclusive
The findings are particularly notable because previous research specifically examining sedentary behavior has not produced a clear answer.
Pei and Marozoff (2025) conducted a systematic review of 12 observational studies examining sedentary behavior in relation to preeclampsia, gestational hypertension or blood pressure during pregnancy.
Overall, the review found little evidence that sedentary behavior was associated with those outcomes.
However, the authors identified an important weakness in the evidence: only two of the included studies objectively measured sedentary behavior. Studies also differed in how sedentary time was defined and measured.
The Pregnancy 24/7 study addresses some of those shortcomings by repeatedly using wearable devices across pregnancy.
This does not invalidate the earlier review. Instead, it provides stronger observational evidence for a relationship that previous research had been unable to establish consistently.
Exercise Trials Tell a More Established Story
Evidence that appropriate exercise during pregnancy can reduce some hypertensive complications is stronger.
In a systematic review and meta-analysis, Magro-Malosso et al. (2017) analyzed 17 randomized trials involving 5,075 pregnant women.
Women assigned during early pregnancy to aerobic exercise for approximately 30 to 60 minutes, two to seven times per week, had a lower incidence of hypertensive disorders overall.
Among the seven trials contributing data to that outcome, hypertensive disorders occurred in 5.9% of women in the exercise groups compared with 8.5% of controls, corresponding to a relative risk of 0.70.
Gestational hypertension occurred in 2.5% of the exercise groups compared with 4.6% of controls.
Preeclampsia alone, however, was not significantly reduced.
A newer systematic review and meta-analysis by Barakat et al. (2024) examined randomized controlled trials published between 2010 and 2023.
The researchers again found that physical activity during pregnancy was associated with a lower risk of maternal hypertensive disorders overall and modest reductions in systolic and diastolic blood pressure. As in the earlier analysis, however, the reduction in preeclampsia itself was not statistically significant.
These randomized trials and the new Pregnancy 24/7 study address related but different questions.
The trials primarily tested whether exercise interventions improved pregnancy outcomes. Pregnancy 24/7 examined how the entire balance of sitting, light movement, more intense activity and sleep was associated with hypertension risk.
Why the New Study Adds Something Different
Taken together, the evidence suggests a potentially important distinction.
Previous randomized trials indicate that structured physical activity can reduce gestational hypertension. Previous studies focusing specifically on sedentary behavior, however, have been inconsistent.
Pregnancy 24/7 strengthens the latter evidence because movement was measured objectively for seven days during each trimester rather than relying primarily on questionnaires or a single measurement.
Another strength is timing. Almost all hypertensive cases were diagnosed after the third-trimester monitoring period, meaning the measured behavior generally preceded the diagnosis.
Still, that does not establish causation.
Women who spend less time sitting may differ from highly sedentary women in diet, health, occupation, socioeconomic circumstances or other factors that could also influence pregnancy outcomes.
The researchers adjusted their statistical models for several factors, including age, race, ethnicity, parity, education, study site and prepregnancy body mass index, but observational studies cannot eliminate every potential confounder.
Could Sitting Less Actually Prevent Preeclampsia?
That remains unknown.
The study provides a reason to test the idea, but an intervention trial would be needed to determine whether deliberately replacing sitting with light activity actually reduces hypertensive disorders.
There are also limitations to how widely the results can be generalized.
Nearly 88% of participants were White, more than three-quarters had at least a college degree, and most had private health insurance. The researchers also lacked a comprehensive assessment of diet.
The study may therefore not fully represent pregnant populations with different racial, socioeconomic or health characteristics.
Another issue is that gestational hypertension and preeclampsia were combined into a broader hypertensive-disorder outcome. Although related, they are not identical conditions, and the study was not large enough to establish detailed movement patterns for each condition separately.
What Should Pregnant Women Take From the Findings?
The study should not be interpreted as a reason to worry whenever a pregnant woman spends a long day sitting.
Nor does it show that someone who sits fewer than 10 hours is protected from preeclampsia.
Instead, it adds to a broader body of research suggesting that movement throughout pregnancy may matter for cardiovascular health. Its distinctive contribution is the possibility that reducing prolonged sedentary time and accumulating more ordinary light movement may deserve attention alongside formal exercise.
For most healthy pregnancies, physical activity recommendations should still be based on established clinical guidance and individual medical circumstances. People with pregnancy complications or conditions affecting their ability to exercise should discuss activity with their healthcare professional.
The scientific question raised by Pregnancy 24/7 is now more specific: if researchers deliberately help pregnant women replace some sedentary time with light activity, will fewer women develop gestational hypertension or preeclampsia?
Until randomized trials answer that question, the new results are best understood as evidence of an association, not proof that sitting for more than 10 hours causes high blood pressure during pregnancy.
Funding and Disclosures
The Pregnancy 24/7 study was funded by the National Institutes of Health and clinical and translational science institutes at the University of Iowa, University of Pittsburgh and West Virginia University.
The authors reported no competing interests.
References
Barakat, R., Silva-Jose, C., Zhang, D., Sánchez-Polán, M., Refoyo, I., & Montejo, R. (2024). Influence of physical activity during pregnancy on maternal hypertensive disorders: A systematic review and meta-analysis of randomized controlled trials. Journal of Personalized Medicine, 14(1), Article 10. https://doi.org/10.3390/jpm14010010
Magro-Malosso, E. R., Saccone, G., Di Tommaso, M., Roman, A., & Berghella, V. (2017). Exercise during pregnancy and risk of gestational hypertensive disorders: A systematic review and meta-analysis. Acta Obstetricia et Gynecologica Scandinavica, 96(8), 921–931. https://doi.org/10.1111/aogs.13151
Pei, L. X., & Marozoff, S. (2025). Sedentary behavior during pregnancy and risk of pre-eclampsia and/or gestational hypertension: A systematic review. International Journal of Gynecology & Obstetrics, 171(1), 106–123. https://doi.org/10.1002/ijgo.70193
Whitaker, K. M., Crisp, A. H., Gallagher, J., Jones, M. A., Kim, J., Wilhite, K., Smith, K., Rahman, S., Thrower, A., Catov, J., Kline, C., Feghali, M., Santillan, D., Santillan, M., Sheikh, I., Zimmerman, B., & Barone Gibbs, B. (2026). Optimal 24-hour movement behaviour compositions across trimesters and risk of hypertensive disorders of pregnancy: The Pregnancy 24/7 cohort study. British Journal of Sports Medicine, 60(16), 1218–1226. https://doi.org/10.1136/bjsports-2025-111091
