The effects of high blood sugar levels on the mother and fetus can be divided into the following aspects: firstly, during early pregnancy, if the blood sugar level is too high, it can affect the growth and development of the embryo and can cause malformations in fetal development or cause the embryo to stop developing and miscarriage. For fetal development malformations, it can mainly cause abnormalities in the development of the heart and nervous system. Secondly, high blood glucose can increase the viscosity of blood and cause vasoconstriction, making the incidence of hypertensive syndrome during pregnancy much higher than that of non-blood glucose normal pregnant women. Finally, high blood glucose can lead to infections of the genital tract and other skin infections, mainly due to the high blood glucose level, which makes it easier for disease-causing microorganisms to grow and may lead to the manifestation of related infections. In addition, prolonged high blood glucose levels can lead to fetal overgrowth, which may result in a giant fetus and excessive amniotic fluid, both of which can increase the burden on the mother’s vital organs and make her prone to pregnancy complications. If the blood glucose is elevated for a long time, it may stimulate the capillary hyperplasia of the placenta, leading to insufficient perfusion of the placenta and fetal distress in the middle and late stages of pregnancy. Gestational diabetes has a genetic component. If a pregnant woman develops gestational diabetes in her first pregnancy, the incidence of gestational diabetes in another pregnancy may be 33%-67%, which means an increased chance of developing the disease by 1/3-2/3. The effects on the fetus may include a large fetus and excessive amniotic fluid, which may increase the risks associated with labor and delivery, such as a large fetus that may cause slow labor and delivery and fetal hypoxia, and excessive amniotic fluid that may cause umbilical cord compression during water breakage, further increasing the incidence of intrauterine hypoxia. Newborns born to mothers with gestational diabetes are prone to fetal respiratory distress syndrome, which is a condition in which the production of lung surface active substances is affected by hyperglycemia and fetal lung maturation is delayed compared to that of normal pregnant fetuses. Studies have found that infants born with gestational diabetes are at a much higher risk of developing hypertension and diabetes in adulthood than normal infants.