Exercise during pregnancy and gestational diabetes-related adverse effects: a randomised controlled trial

Objective To examine the effect of regular moderate-intensity exercise (three training sessions/week) on the incidence of gestational diabetes mellitus (GDM, primary outcome). We also examined if the exercise intervention modifies the association between GDM and birth weight and risk of macrosomia, gestational age, risk of caesarean delivery and maternal weight gain (secondary outcomes). Methods We randomly assigned 510 healthy gravida to either an exercise intervention or a usual care (control) group (n=255 each). The exercise programme focused on moderate-intensity resistance and aerobic exercises (three times/week, 50-55 min/session). GDM diabetes was diagnosed according to the WHO criteria and the International Association for Diabetes in Pregnancy Study Group (IADPSG). Results The intervention did not reduce the risk of developing GDM (OR 0.84, 95% CI 0.50 to 1.40) when using the WHO criteria. We observed that the intervention reduced by 58% the GDM-related risk (WHO criteria) of having a newborn with macrosomia (OR 1.76, 95% CI 0.04 to 78.90 vs 4.22, 95% CI 1.35 to 13.19) in exercise and control groups, respectively), and by 34% the GDM-related risk of having acute and elective caesarean delivery (OR 1.30, 95% CI 0.44 to 3.84 vs 1.99, 95% CI 0.98 to 4.06 in exercise and control groups, respectively). Gestational age was similar across the treatment groups (control, exercise) and GDM category (GDM or non-GDM), and maternal weight gain was similar to 12% lower in the exercise group independent of whether women developed GDM. The results were similar when the IADPSG criteria were used instead. Conclusions Regular moderate-intensity exercise performed over the second-third trimesters of pregnancy can be used to attenuate important GDM-related adverse outcomes.