High sugar levels in your blood can be unhealthy for both you and your baby. If the diabetes isn't treated, your baby may be more likely to have problems at birth. For example, your baby may have a low blood sugar level or jaundice, or your baby may weigh much more than is normal. Gestational diabetes can also affect your health. For instance, if your baby is very large, you may have a more difficult delivery or need a cesarean section.