Prophylactic Metformin in Obese Non-Diabetic Pregnant Women: Effects on Gestational Weight Gain, Preeclampsia, and Neonatal Outcomes

Maternal obesity is a major global health problem associated with increased maternal and neonatal morbidity, including gestational diabetes mellitus (GDM), preeclampsia, excessive gestational weight gain, and adverse fetal outcomes. Metformin, an insulin-sensitising agent widely used in type 2 diabetes mellitus and polycystic ovary syndrome (PCOS), has been proposed as a preventive therapy during pregnancy. This randomised, placebo-controlled trial evaluated the effect of prophylactic metformin on gestational weight gain and preeclampsia in obese, non-diabetic pregnant women. A total of 150 women with a body mass index (BMI) ≥ 30 kg/m² were recruited between 12 and 20 weeks of gestation at Basra Maternity and Child Hospital and allocated to receive either metformin 500 mg once daily (n = 75) or a matching placebo (n = 75) from the 12th week of gestation until delivery. Maternal metabolic parameters, gestational weight gain, obstetric complications, and neonatal outcomes were assessed, and data were analysed using SPSS version 21. Metformin significantly reduced mean gestational weight gain compared with placebo (4.6 kg versus 6.3 kg; P = 0.01) and lowered the incidence of preeclampsia (P = 0.01). No significant differences were observed in fasting blood glucose, the homeostatic model assessment of insulin resistance (HOMA-IR) at 36 weeks, caesarean section rate, postpartum haemorrhage, birth weight, Apgar scores, or neonatal intensive care unit (NICU) admissions. Low-dose prophylactic metformin appears to be a safe and effective intervention for reducing excessive gestational weight gain and preeclampsia in obese, non-diabetic pregnancies without adversely affecting neonatal outcomes.