Diabetes in a pregnant woman can affect the developing baby throughout the pregnancy. In early pregnancy, maternal diabetes can result in birth defects and an increased rate of miscarriage. Many of the birth defects that occur affect major organs such as the brain and heart.
During the second and third trimester, maternal diabetes can lead to over-nutrition and excess growth of the baby. Having a large baby increases risks during labor and delivery. For example, large babies often require caesarean deliveries and if he or she is delivered vaginally, they are at increased risk for trauma to their shoulder.
In addition, when fetal over-nutrition occurs and hyperinsulinemia results, the baby's blood glucose can drop very low after birth, since it won't be receiving the high blood glucose from the mother.
However, with proper treatment, you can deliver a healthy baby despite having gestational diabetes.