Strength training in pregnancy improved quality of life; the diabetes result fell short
In short
In a randomized trial of 209 pregnant women with a BMI of 25 or above, the intervention group followed a strength training program combining supervised and home-based sessions from gestational weeks 12-14 until week 36 or delivery. Quality of life improved significantly (mean difference 8.4; 95% CI 4.9 to 11.9; p < 0.001) and participants reported lower frequency and impact of pregnancy symptoms. The primary outcome, gestational diabetes incidence, showed an absolute risk difference of -5.3% (95% CI -12.5 to 0.5; p = 0.07), which did not reach statistical significance. No differences were seen in adverse events, including preterm birth.
This trial set out to prevent gestational diabetes, and on that primary outcome it did not reach statistical significance. Something else did improve, unambiguously — quality of life (mean difference 8.4; 95% CI 4.9 to 11.9; p < 0.001). Reading those two in the right order is how to read this study.
How was it run?
A randomized clinical trial of 209 pregnant women with a body mass index of 25 or above (ClinicalTrials.gov NCT05840497). The intervention group followed a strength training program combining supervised and home-based sessions from gestational weeks 12-14 until week 36 or delivery. The primary outcome was gestational diabetes incidence; secondary outcomes covered gestational weight gain, macrosomia, physical activity, quality of life, and pregnancy symptoms.
What happened with gestational diabetes?
The intervention group had lower incidences of gestational diabetes and hydramnios, but the absolute risk differences were -5.3% (95% CI -12.5 to 0.5; p = 0.07) and -4.5% (95% CI -11.0 to 2.0; p = 0.05) — short of the significance threshold. In the per-protocol analysis, gestational diabetes incidence was 0% among adherent intervention participants against 7.3% in controls, though that too came in at p = 0.09. The direction is consistent, but this sample cannot settle it, which is what the authors conclude.
Why did it fall short?
Adherence is the clue. Only 48% of the intervention group hit the adherence target. Strength training was chosen in the first place because it was expected to achieve higher adherence than aerobic protocols, and it still landed just under half. Read alongside the 0% gestational diabetes rate in the adherent subgroup, the bottleneck here looks less like whether the intervention works and more like how much of it actually gets done.
What clearly improved
Quality of life improved significantly in the intervention group (mean difference 8.4; 95% CI 4.9 to 11.9; p < 0.001), and participants reported lower frequency and impact of pregnancy-related symptoms. No differences were observed in adverse events, including preterm birth. The program made the pregnancy more livable, and did so without moving the safety indicators the wrong way.
Participants had a BMI of 25 or above, and the program included supervised sessions. Exercise during pregnancy depends on individual history and how the pregnancy is progressing, so starting or changing anything belongs in a conversation with your clinician. The unmet primary outcome should also be taken at face value — the authors state a preventive effect needs confirmation in larger trials.
About logging during this period
Muscle Index corrects for bodyweight to produce a relative strength score. Pregnancy changes the conditions that correction assumes, so a score from this period does not sit meaningfully next to your earlier records or anyone else's. What remains is not the score but how many sessions got completed — which is exactly the variable that decided this trial. For lifting through pregnancy generally see lifting during pregnancy, and for intra-abdominal pressure and pelvic floor concerns, powerlifting and the pelvic floor.
Frequently asked questions
Does strength training during pregnancy prevent gestational diabetes?
This trial did not establish it. The intervention group had a lower incidence, but the absolute risk difference of -5.3% (95% CI -12.5 to 0.5; p = 0.07) did not reach statistical significance, and the authors say a preventive effect needs confirmation in larger trials.
What did improve significantly?
Quality of life, with a mean difference of 8.4 (95% CI 4.9 to 11.9; p < 0.001) in the intervention group. Participants also reported lower frequency and impact of pregnancy-related symptoms.
When did the program run?
From gestational weeks 12-14 until week 36 or delivery, combining supervised and home-based sessions, in 209 pregnant women with a body mass index of 25 or above.
Was strength training safe during pregnancy?
No differences in adverse events, including preterm birth, were observed in this trial. Decisions still depend on individual history and pregnancy progression, so consult your clinician before starting.
Why does adherence matter here?
Only 48% of the intervention group reached the adherence target. In the per-protocol analysis of adherent participants, gestational diabetes incidence was 0% against 7.3% in controls, suggesting how much training actually happened drove the result.
Source: PubMed