Gestational diabetes can affect the baby but because it occurs in late pregnancy (around 28 weeks) it does not result in severe birth defects. If a mother has gestational diabetes, it can lead to over-nutrition and excess growth of the baby, increasing risks during labour and delivery. After birth, the baby's blood sugar can drop very low because it won't be receiving high blood sugar from the mother. However, with proper treatment you can deliver a healthy baby even if you have diabetes.
Attribution: Straight Talk Foundation