Obese nondiabetic women randomly assigned to receive metformin during pregnancy gained less weight than those who did not take the drug, but they were no less likely to have large-for-gestational-age (LGA) neonates, a study published in the February 4 issue of the New England Journal of Medicine shows.
Because metformin improves insulin sensitivity and has been shown to reduce weight gain in pregnant patients with gestational diabetes, Argyro Syngelaki, PhD, from the Harris Birthright Research Centre for Fetal Medicine, King’s College Hospital, London, United Kingdom, and colleagues hypothesized the drug might lead to a lower median neonatal birth weight z score when given to nondiabetic pregnant women with a body mass index of more than 35 kg/m2.
To test the hypothesis, the researchers enrolled 450 obese pregnant women without diabetes in the double-blind, placebo-controlled Metformin in Obese Nondiabetic Pregnant Women (MOP) trial. Of the 450 women, 225 were randomly assigned to receive a maximum of 3.0 g metformin per day from 12 to 18 weeks of gestation through delivery, and 225 were assigned to receive a placebo.
A total of 50 women withdrew consent during the trial, which left 202 women in the metformin group and 198 in the placebo group, the study authors report.
“There were no significant differences between the metformin group and the placebo group in the median neonatal birth-weight z score, the incidence of large-for-gestational-age neonates, or the incidence of adverse fetal or neonatal outcomes,” they write.