1 Urmia University of Medical Sciences, Urmia, Iran.

2 Department of Biostatistics and Epidemiology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran

3 Department of Obstetrics and Gynecology, School of Medicine, Shahid Motahari Hospital, Urmia University of Medical Sciences, Urmia, Iran


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 360 pregnant women at 12-16 gestational weeks who referred to the gynecology clinic of Motahari hospital, Urmia, Iran, during 2019 to 2020. The intervention group received 1000 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 180 patients, 169 patients remained in the intervention group and 171 patients remained in the control group based on the eligibility criteria. In the control group, 13 patients (7.6%), and in the intervention group, five patients (2.9%) had preeclampsia and high blood pressure during pregnancy (P= 0.053). In the control group, the mean maternal weight gain during pregnancy was 10.22 ± 3.3  kg and in the intervention group was 7.6 ± 2.3 kg (P <0.001). The two groups were homogeneous regarding gravity, parity, abortion (P>0.05).
The administration of 1000 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.