To evaluate the influence of gestational diabetes mellitus on neonatal birthweight, macrosomia and weight discrepancy in twin neonates METHODS: An observational retrospective study was performed. One hundred and six women with gestational diabetes and twin pregnancy and 166 twin controls who delivered viable fetuses > 24 weeks were included. Impact of maternal pre-pregnancy BMI, smoking habit, method of conception, chorionicity, gestational age at delivery, mode of delivery and hypertensive complications were also analysed. The effect of maternal hyperglycaemia and metabolic control in gestational diabetes pregnancies was assessed.