The reasons for the newborn’s blue buttocks mainly include the following two cases: 1, caused by the birthmark of the newborn, is the most important and common reason for the newborn’s blue buttocks. The newborn’s buttocks are green since birth. In addition to the blue buttocks, the newborn has normal development and good mental state, so no special treatment is needed. The newborn’s blue buttocks will slowly reduce or subside as the newborn’s age increases; 2. The newborn’s poor blood circulation is caused by severe infection or trauma. If the newborn is traumatized, it will cause poor local blood circulation in the buttocks, thus causing the symptoms of skin bruising. If the newborn has a serious infection, it will not only cause the blue buttocks, but also cause the pattern of other skin parts of the body and the blue situation, so we should promptly carry out anti-infection and blood circulation treatment for the newborn.