Infants born with green buttocks may be caused by Mongolian spots, trauma and coagulation disorders. 1. Mongolian spots: most newborns with green buttocks may be related to Mongolian spots, which are mainly manifested as green birthmarks on the buttocks, back and other skin. 2. trauma: may be infants in the birth process, the buttocks by the outside world caused by the injury, there may be infants born buttocks green phenomenon. 3. Coagulation disorders: if the baby suffers from coagulation disorders, or capillary fragility increases, capillary rupture leads to subcutaneous bleeding, there will often be buttocks skin bruising symptoms appear. If a baby is born with a blue butt, it is recommended that the baby be taken to the hospital for a relevant examination to determine the cause of the disease and then under the guidance of the doctor to carry out the appropriate treatment and therapy.