RESUMEN
OBJECTIVE: To evaluate the effectiveness of an exercise programme for pregnant women who were overweight or obese and at risk for gestational diabetes mellitus (GDM). DESIGN: Randomised controlled trial. SETTING: Hospitals and midwifery practices in the Netherlands. POPULATION: Pregnant women who were overweight or obese and at risk for GDM between 2007 and 2011. METHODS: Normal care was compared with an exercise training programme during pregnancy. The training consisted of aerobic and strength exercises, and was aimed at improving maternal fasting blood glucose, insulin sensitivity, and birthweight. Linear regression analyses were performed to determine the effects. MAIN OUTCOME MEASURES: Maternal outcome measures were fasting blood glucose (mmol/l), fasting insulin (pmol/l) and HbA1c (%), body weight (kg), body mass index (kg/m(2) ), and daily physical activity (minute/week). Offspring outcome measures were birthweight and fetal growth. RESULTS: A total of 121 women were randomly allocated to either a control (n = 59) or an intervention (n = 62) group. Intention-to-treat analysis showed that the exercise programme did not reduce maternal fasting blood glucose levels nor insulin sensitivity. Also, no effect was found on birthweight. CONCLUSIONS: The exercise intervention performed over the second and third trimester of pregnancy had no effects on fasting blood glucose, insulin sensitivity, and birthweight, most probably because of low compliance. The high prevalence of women at risk for GDM calls for further research on possible interventions that can prevent GDM, and other types of interventions to engage this target group in physical activity and exercise.