The Study
Resistance Training Does Not Decrease Placental Blood Flow During Valsalva Maneuver: A Novel Use of 3D Doppler Power Flow Ultrasonography
This study watched 22 pregnant athletes lift weights and measured blood flow to the baby before and after. It found a tiny change, but it didn't test if lifting weights actually causes better or worse outcomes—it just saw what happened when they did it.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Scientists checked if lifting weights while pregnant reduces blood flow to the baby, using a special ultrasound that sees blood flow in the placenta.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 547 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Even though lifting causes a strain, this tiny increase in blood flow means the baby isn’t being starved — it might even get a little more blood.
- 2Blood flow to the placenta went up a little — from 2.071 to 2.185 — when women lifted weights up to 50 lbs.
- 3Women who exercised regularly had an even bigger increase.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Sports Health: A Multidisciplinary Approach
Year
2021
Authors
Sara J. Gould, C. Cawyer, Louis A. Dell’Italia, Lorie M. Harper, G. McGwin, M. Bamman
Related Content
Claims (8)
Doing the Valsalva maneuver—like holding your breath and bearing down—while lifting weights during pregnancy doesn’t reduce blood flow to the baby or lower the baby’s oxygen levels.
Pregnant women who regularly work out and do strength training may see better blood flow to the placenta during their workouts compared to other pregnant women, which could help the baby get more oxygen and nutrients.
Lifting weights up to 50 pounds while pregnant doesn't hurt blood flow to the baby—and might even help it a little—so the idea that lifting is always dangerous for the baby might not be true.
A special ultrasound technique can pick up tiny changes in blood flow to the placenta when a pregnant woman does strength training, which might help doctors watch over the baby's blood supply during workouts.
When pregnant athletes do weight training, their blood flow to the placenta temporarily goes up a little bit — and that’s a good thing because it means the baby isn’t getting less blood than it needs.
When pregnant women who regularly work out lift light to moderate weights (up to 50 lbs), their baby’s blood flow doesn’t drop—it actually goes up a little bit during the lift, which means it’s probably safe for them to do these exercises without worrying about cutting off the baby’s blood supply.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.