Hi Sarah

When you have gestational diabetes, your pancreas works overtime to produce insulin, Insulin does not lower your blood glucose levels it helps your body to yse the insulin which is needed for energy. Insulin does not cross the placenta, but glucose and other nutrients do. So extra blood glucose goes through the placenta, giving the baby high blood glucose levels. This causes the baby's pancreas to make extra insulin to get rid of the blood glucose. Since the baby is getting more energy than it needs to grow and develop, the extra energy is stored as fat. This can lead to having a big baby. Big babies face health problems of their own, including damage to their shoulders during birth. Because of the extra insulin made by the baby's pancreas, newborns may have very low blood glucose levels at birth and are also at higher risk for breathing problems and jaundice. Babies with excess insulin become children who are at risk for obesity and adults who are at risk for type 2 diabetes.

If you need any more info let me know.