Since high blood sugar in pregnant mothers can have many adverse effects on this mother’s and the fetus is. Therefore, when a pregnant mother has high blood sugar, it is important to control the blood sugar to normal level, that is, to meet the standard, in order to prevent the impact of these high blood sugar on the mother and the fetus. First of all, it is harmful to the mother like gestational hypertension, eclampsia, infection or the emergence of a huge baby after the surgery period, the increase of birth injuries, and also ketoacidosis, which can occur. Effects on the fetus. First of all, high blood sugar can cause gigantism, fetal malformation, congenital heart disease, anencephaly, hydrocephalus, intrauterine fetal death, etc. Complications in newborns, such as neonatal hypoglycemia, neonatal hyperbilirubinemia, neonatal respiratory distress syndrome, etc., can occur. This and hypocalcemia may also occur in newborns. There is also a possibility that during pregnancy, hyperglycemic restraint, excessive amniotic fluid, premature birth, miscarriage, stillbirth, intrauterine distress, all of which are likely to occur. But it’s the high blood sugar that has so many dangers to the mother and child during pregnancy. There are also long-term effects on the mother, such as gestational diabetes, which has a high recurrence rate, an increased chance of developing diabetes, and an increased risk of metabolic syndrome. For example, the incidence of abnormal glucose tolerance is higher, and children are more likely to be obese, and the incidence of metabolic syndrome is increased, and there is also a possibility of neuropsychiatric developmental disorders. In conclusion, high blood sugar in pregnant mothers must be controlled to prevent harm to the fetus and to the mother.