Heavy Lifting in Pregnancy: New Study Finds No Harm to Baby
Largest study to date shows trained women can lift heavy — even on their backs, without affecting fetal heart or blood flow.
📢 Quick heads-up: For the rest of the month, you can lock in a lifetime subscription to Strength Science. That’s a one-time payment for unlimited access to the FULL archive. Grab it here and enter this coupon code bfss for a little treat. 💪
This study, titled “Pushing limits: The acute effects of a heavy-load resistance protocol and supine exercise on fetal well-being” explored how heavy weightlifting affects fetal heart rate and blood flow in pregnant athletes. It’s the largest experimental study ever to test whether women can safely lift heavy during pregnancy — a question that has long divided coaches, doctors, and mothers alike.
Key Points
Aim
The aim was to examine the acute effects of heavy-load resistance training, including supine exercise (bench press), on fetal heart rate (FHR) and uteroplacental blood flow in elite and recreational pregnant athletes during late pregnancy (26–35 weeks gestation).
Methods
Participants: 48 healthy pregnant athletes (7 elite, 41 recreational), all exercising ≥4 hours/week.
Protocol: Each performed three compound lifts — sumo deadlift, bench press, and incline bench press — for 3 sets of 8 reps at roughly 76% of 1RM (one repetition in reserve).
Measurements: Ultrasound recorded FHR and uterine/umbilical artery pulsatility index (PI) before and after each lift. Symptoms of vena cava syndrome (e.g. dizziness or nausea) were documented.
Safety stop: Protocol halted if FHR <110 bpm for 3 minutes or >180 bpm.
Results
Normal heart rates: FHR remained within the healthy range (110–160 bpm) across all exercises.
Mild increases: Small, statistically significant rises in FHR followed sumo deadlift (p=0.002) and incline bench press (p=0.008), but not after flat bench press (p=0.122).
Improved blood flow: Uterine artery PI decreased after all three exercises — suggesting enhanced uterine blood flow, not restriction.
Stable umbilical flow: No changes occurred in umbilical artery PI.
Minor incidents:
One case of transient fetal bradycardia (79–91 bpm) after bench press — resolved spontaneously within 3 minutes.
4–5 cases of mild fetal tachycardia per exercise, none beyond safe levels (<180 bpm).
One athlete reported dizziness (vena cava symptoms), but fetal data remained normal.
No difference between supine (flat bench) and incline press in fetal outcomes.
Key Findings
No adverse effects on fetal well-being from heavy-load lifting or brief supine exercise in healthy, resistance-trained women.
Experienced lifters showed slightly more stable fetal responses than those newer to heavy training.
FHR, uterine, and umbilical blood flow all remained within safe physiological ranges.
Practical Applications
For trained pregnant lifters:
Heavy lifting (≈75% 1RM) — even in the third trimester — can be performed safely under supervision, when technique and breathing are controlled.
Supine lifts (bench press) are not necessarily harmful, especially when brief (sets lasting ~30s) and performed with proper rest.
Symptoms (dizziness, breath-holding) should pause or modify exercise (e.g. incline positioning).
Builds evidence toward modern, evidence-based prenatal lifting guidelines.
Limitations
Only included highly active, healthy women — results may not generalise to less conditioned individuals.
The study only measured short-term effects — not chronic training outcomes.
Breathing strategy (Valsalva) wasn’t recorded, which is an important consideration for future studies.
Key Takeaways
Heavy-load lifting can be safe for trained pregnant women with medical clearance.
Fetal heart rate and blood flow remain stable, even under high load.
Supine pressing is not automatically risky, though monitoring symptoms remains essential.
Training experience matters more than athlete status — familiarity drives safer responses.
Findings challenge outdated “no heavy lifting” pregnancy advice and favour updated, evidence-based strength guidelines.
Reference
Dalhaug EM, Sanda B, Bø K, Brown W, Haakstad LAH. Pushing limits: the acute effects of a heavy-load resistance protocol and supine exercise on fetal well-being. BMJ Open Sport & Exercise Medicine. 2025;11:e002639. https://doi.org/10.1136/bmjsem-2025-002639
You can also find me at dannyleejames.com for stories, personal training insights, and coaching.
Book a call with me here.
We’ll sit down and build out your entire training and performance program in one session.