In wealthy countries, ~50% of women are overweight or obese when they become pregnant, putting mother and baby at risk of a range of adverse outcomes.

The multicentre, randomised, double-blind, placebo-controlled GRoW (Metformin for Gestational Restriction of Weight in Pregnant Women) trial studied the potential use of metformin to reduce pregnancy weight gain and improve outcomes. Dodd et al. studied more than 500 overweight or obese women (body mass index ≥25 kg/m²) at 10–20 weeks’ gestation from three public maternity units in Adelaide, SA, Australia. Metformin (≤2000mg per day) had no significant effect on the proportion of infants with birthweight >4000g compared with placebo, but did reduce weekly pregnancy weight gain. Total gestational weight gain, pregnancy and birth outcomes, and maternal diet, physical activity, quality of life and emotional well-being, did not differ significantly between groups.

For overweight or obese pregnant women, metformin given in addition to dietary and lifestyle advice from 10 to 20 weeks’ gestation does not appear to improve outcomes. The authors suggest a focus on dietary and lifestyle interventions before pregnancy ‘to break the cycle of intergenerational obesity’.

Read the full article in Lancet Diabetes & Endocrinology 7 P15–P24