Comparison of Newborn Outcomes in Women with Gestational Diabetes Mellitus Treated with Metformin or Insulin: A Randomised Blinded Trial

background: few studies have been done on the use of metformin in pregnancy and their results were not similar, therefore this research is performed to compare neonatal outcomes of metformin and insulin in the treatment of gestational diabetes. methods: in this prospective randomized trial, 200 pregnant women within their 24th to 34th weeks of gestation with gestational diabetes, single fetus pregnancy, and in need of hyperglycemia treatment were entered and grouped as either metformin or insulin. data related to maternal and neonatal outcomes were recorded and analyzed. results: considering data recorded of hba1c at the beginning of pregnancy, pregnancy induced hypertension, preeclampsia, birth weight, dystocia, first and 5th min apgar, neonatal sepsis, rout of delivery, liver function tests of neonate, hypoglycemia, anomaly, and still birth, there were no significant statistical differences between groups. the end pregnancy hba1c, maternal weight gain during pregnancy, preterm labor, neonatal jaundice, respiratory distress and hospitalization of infants were higher in insulin group. conclusions: considering data from this study, metformin is efficient to control hyperglycemia in pregnancy. it is suggested performing more studies to evaluate long term side effects of metformin in pregnancy with higher sample size and longer follow-up of newborns.