Huge baby refers to the baby’s birth weight ≥4kg, physiological huge baby will also account for part of the baby, such as the height of a relatively tall pregnant women to deliver huge baby, generally intelligence is not affected. If gestational combined diabetes mellitus and the blood sugar is not well controlled during pregnancy, especially in late pregnancy, and when the blood sugar control during pregnancy is not good, it may cause a giant fetus. If the blood sugar is high in early pregnancy, there will be abnormal development of the nervous system, or there is hypoplasticity in late pregnancy, which may lead to chronic hypoxia in the fetus in utero, and if the chronic hypoxia is long, it may lead to abnormal development of fetal intelligence.