Efficacy of Metformin on Pregnancy Outcome in Healthy Overweight Pregnant Women; A Double-Blinded Parallel Randomized Clinical Trial

Background Maternal obesity increases the risk of pregnancy complications such as preeclampsia, postpartum hemorrhage, weight gain and the need for cesarean section. We compared the role of metformin on pregnancy outcome in overweight mothers. Materials and Methods: This double-blinded parallel randomized clinical trial was carried out on ۳۶۰ pregnant women at ۱۲-۱۶ gestational weeks who referred to the gynecology clinic of Motahari hospital, Urmia, Iran, during ۲۰۱۹ to ۲۰۲۰. The intervention group received ۱۰۰۰ mg of metformin orally every day up to the end of pregnancy. Demographic and clinical characteristics of patients such as age, gravidity, parity, preterm infant weight, live birth, abortion, previous delivery method, maternal weight, body mass index, birth weight, delivery method, blood sugar at birth, gestational age at birth, neonatal hypoglycemia, infant mortality and anomalies were also recorded. Finally, the pregnancy outcomes (gravidity, parity, abortion and weight) were compared between the two groups. Results: Of ۱۸۰ patients, ۱۶۹ patients remained in the intervention group and ۱۷۱ patients remained in the control group based on the eligibility criteria. In the control group, ۱۳ patients (۷.۶%), and in the intervention group, five patients (۲.۹%) had preeclampsia and high blood pressure during pregnancy (P= ۰.۰۵۳). In the control group, the mean maternal weight gain during pregnancy was ۱۰.۲۲ ± ۳.۳  kg and in the intervention group was ۷.۶ ± ۲.۳ kg (P <۰.۰۰۱). The two groups were homogeneous regarding gravity, parity, abortion (P>۰.۰۵). Conclusion The administration of ۱۰۰۰ mg metformin daily has been shown to be effective in preventing overweight in pregnancy, but has not affected the birth weight. Metformin did not have any side effects on pregnancy outcomes.