Cardiovascular effects of exercise training in pregnant people with a high body mass index: secondary results from a randomised controlled trial (ETIP).

Objectives: We aimed to determine the effectiveness of exercise training during pregnancy on peak oxygen uptake (V̇O₂peak), cardiac function and flow-mediated dilatation (FMD) of the brachial artery throughout pregnancy and post partum in individuals with a prepregnancy body mass index (BMI) ≥28 kg/m².

Trial design: Parallel-group randomised controlled trial (RCT).

Methods: The exercise group in the Exercise Training in Pregnancy (ETIP) RCT was offered 3 weekly supervised exercise sessions comprising 35 min of moderate-intensity treadmill walking followed by 25 min of strength exercises. The intervention started in gestational weeks 12-18 and continued throughout pregnancy. We measured V̇O₂peak and FMD at baseline, in gestational weeks 34-37 and 3 months post partum and offered echocardiography in gestational weeks 14, 20, and 32, and 6-8 weeks postpartum.

Results: Of the 91 participants included in ETIP, 87 participants (age: 31.3±4.2 years, BMI: 34.6±4.3 kg/m²) provided data on V̇O₂peak, cardiac function and/or FMD. There was no statistically significant effect of exercise training on V̇O₂peak in gestational weeks 34-37, with an estimated effect of 1.7 mL/min/kg (95% CI -0.4 to 3.7, p=0.112) or post partum (1.6 mL/min/kg, 95% CI -0.2 to 3.4, p=0.079), compared with the control group. There were no statistically significant between-group differences in either FMD or any of the echocardiographic outcomes. Only 50% of the participants in the exercise group fulfilled our prespecified adherence criteria.

Conclusion: Offering pregnant individuals with BMI ≥28 kg/m², a supervised exercise intervention did not improve cardiorespiratory fitness, cardiac function or FMD.

Trial registration number: NCT01243554.