Childhood Follow-up of the GRoW Randomized Trial: Metformin in Addition to Dietary and Lifestyle Advice for Pregnant Women with Overweight or Obesity

Background: Metformin for women with overweight or obesity during pregnancy has been evaluated in randomized trials to reduce adverse pregnancy and birth outcomes. The effect on longer-term child health remains of interest.

Objectives: To evaluate the effect of in-utero exposure to metformin on child health compared with no exposure.

Methods: We assessed children born to 513 women who participated in the Metformin in addition to dietary and lifestyle advice for pregnant women with overweight or obesity: the GRoW randomized trial, where women were randomized to receive either metformin or placebo during pregnancy. Child weight, height, anthropometry, diet, physical activity and neurodevelopment were assessed at six and 18 months and three to five years of age. The main outcome was BMI z-score > 85th centile for age and sex.

Results: The number of children with BMI >85th centile was similar between treatment groups at all time points. At 18 months and three to five years of age, more than half of the children had a BMI z-score > 85th centile, indicating a high risk of childhood obesity.

Conclusions: We did not show evidence of the benefit of metformin for children of women with overweight or obesity during pregnancy adding to the growing literature on the lack of effect of pregnancy interventions in reducing longer-term risks of childhood obesity.