By Jane Lewis
Metformin given in addition to dietary and lifestyle advice does not improve pregnancy and birth outcomes in overweight or obese pregnant women, an Australian randomised controlled trial has concluded.
Lead study author, Professor Jodie Dodd, maternal fetal medicine specialist at the Women’s and Children’s Hospital, Adelaide, told Medicine Today that in high income countries such as Australia, almost 50% of women are over weight or obese when they become pregnant. ‘This places the mother and her infant at risk of a range of poor outcomes, and can lead to high infant birth weight, which in turn can lead to childhood obesity,’ she said.
The Adelaide based trial, published in the Lancet Diabetes and Endocrinology, enrolled 524 women at 10 to 20 weeks’ gestation with a BMI of 25 kg/m2 or higher (median, 32.32 kg/m2), and randomly assigned them to receive either metformin (maximum dosage, 2000 mg daily) or placebo. All women were given advice on healthy diet and lifestyle.
Compared with women taking placebo, those receiving metformin had lower average weekly gestational weight gain (adjusted mean difference, –0.08 kg) and were more likely to have gestational weight gain below the US International Institute of Medicine’s recommendations. However, no significant difference between the two groups was seen in total gestational weight gain, the proportion of infants with birthweight greater than 4000 g or other pregnancy and birth outcomes.
‘The use of metformin in this clinical setting should not be advocated,’ the authors concluded.
According to Professor Dodd, a new approach is needed to improve pregnancy and birth outcomes in overweight women. ‘Overall, dietary interventions in pregnancy have not been effective,’ she said. ‘We now know that metformin is also not effective, either alone or when combined with dietary advice. Our focus needs to change to evaluating whether helping women achieve weight loss before they conceive is an effective strategy to improve outcomes.’
The author of an accompanying comment agreed, suggesting that modest postpartum weight loss in obese women before a planned pregnancy might be a potential option, although difficult in practical terms. However, it ‘might be the first step in breaking the vicious cycle of maternal obesity begetting obesity in the offspring,’ he concluded.
Lancet Diabetes Endocrinol 2018; http://dx.doi.org/10.1016/S2213-8587(18)30310-3.
Lancet Diabetes Endocrinol 2018; http://dx.doi.org/10.1016/S2213-8587(18)30337-1.