High glucose tolerance means that the pregnant woman has abnormal OGTT test results in the middle of pregnancy, suggesting gestational diabetes, which without control will have adverse effects on the fetus, such as excessive or restricted fetal development, fetal distress, malformation, etc. I. Risks in fetal period: 1. Excessive development: the fetus is in the environment of hyperinsulinemia caused by maternal hyperglycemia for a long time, which promotes fat synthesis and leads to excessive trunk development. Due to the huge size of the fetus at birth, the mother and the baby are prone to complications; 2. Restricted growth: hyperglycemia in early pregnancy has the effect of inhibiting embryonic development and leads to backward development of the embryo. In the case of diabetes combined with microangiopathy, the placental blood vessels are often abnormal, which affects the fetal development; 3, stopping development: pregnant women with hyperglycemia combined with hypertension during pregnancy are prone to fetal distress, and in serious cases, the fetus may stop developing, manifesting as miscarriage or preterm delivery, of which the incidence of preterm delivery is 10%-25%; 4, malformation: in pregnant women with uncontrolled diabetes, the incidence of serious fetal malformation is 7-10 times that of normal pregnancy. It is closely related to the high blood sugar level in the first weeks after conception and is an important cause of perinatal death. Second, postnatal risk of fetus: 1, neonatal respiratory distress syndrome: the incidence is increased, hyperglycemia stimulates the increase of fetal insulin secretion, forming hyperinsulinemia, the latter has the role of antagonizing glucocorticoid, promoting the synthesis and release of alveolar type I cell surface active substance, so that the fetal lung surface active substance production and secretion is reduced, and fetal lung maturation is delayed; 2, neonatal hypoglycemia: the newborn is separated from the maternal After hyperglycemic environment, hyperinsulinemia still exists, and if sugar is not supplemented in time, hypoglycemia is likely to occur and endanger the life of the newborn in serious cases.