Effect of a preconception lifestyle intervention on cardiometabolic outcomes in females at increased risk for gestational diabetes: a randomised controlled trial

Abstract Background Gestational diabetes (GDM) is associated with an increased risk of maternal type 2 diabetes and cardiometabolic diseases in the child. Lifestyle interventions in pregnancy usually start in the second trimester. However, adherence is poor and the evidence of clinically meaningful effects of these interventions are inconclusive. Alternative preconception lifestyle interventions such as time-restricted eating and high-intensity exercise may improve cardiometabolic outcomes, as it does in non-pregnant individuals. Purpose We aim to determine the effect of a preconception lifestyle intervention continued throughout pregnancy, on maternal glucose tolerance and other maternal and infant cardiometabolic outcomes. Methods In this ongoing randomised controlled trial, 167 females at increased risk of GDM contemplating pregnancy were randomly allocated 1:1 to an intervention or control group. The intervention consists of exercise and time-restricted eating. We use a heart rate-based app (Personal Activity Intelligence; PAI) and encourage the participants to maintain ≥ 100 PAI points weekly, corresponding to ≥ 1 hour of weekly exercise at ≥ 80% of individual heart rate maximum. Time-restricted eating involves limiting the time-window for energy intake each day to ≤ 10 hours, ≥ 5 days/week. Maternal and offspring outcomes are measured before, during, and after pregnancy. The primary outcome is glucose tolerance in gestational week 28. Secondary outcomes include body composition and cardio-metabolic outcomes in mothers and their offspring. We used linear mixed models to determine the effect of the intervention, compared with the control group, using the "intention to treat principle". For the primary outcome measure, we set the significance threshold at p <.05. For secondary outcomes, we set this threshold to p <.01 due to multiple comparisons. Here we report preliminary findings from the study. Results One hundred and eleven participants, aged 29.7 ± 3.3 years, conceived within 3.2 ± 2.9 months of randomization. Preliminary analyses show that the participants maintained an average of 83.8 ± 45.1 PAI points throughout the intervention period. There was a significant reduction in the eating window from baseline in the intervention group compared to control (-1.14 hrs, 95% confidence interval -1.70 to -0.58, p <.001). The intervention group lost 2.16 kg (95% confidence interval -3.8 to -0.5, p =.011) compared to the control group in gestational week 28. Favourable, but statistically insignificant, changes were observed in several cardiometabolic parameters, including fat mass, visceral fat area, fasting blood glucose, and HbA1c in the intervention group. Conclusion Our findings suggest that a combination of time-restricted eating and exercise started before and continued throughout pregnancy had no significant effect on glycaemic outcomes or other cardiometabolic health parameters in females with increased risk of GDM.