The cause of black and yellow color of newborns may be due to physiological jaundice, pathological jaundice and other reasons. 1. Physiological jaundice: mainly due to the metabolic increase of erythrocytes caused by the low oxygen environment in the uterus, the increase of blood oxygen level after birth leads to a large number of erythrocytes being destroyed, resulting in the elevation of bilirubin. The unique enterohepatic circulation of the newborn and the immaturity of liver function lead to bilirubin not being converted, which leads to physiological jaundice of the newborn, thus making the newborn black and yellow. 2. Pathological jaundice: neonatal infection, hemolysis, asphyxia, acidosis, congenital biliary atresia and other causes may lead to excessive production of bilirubin or metabolic abnormality, which leads to elevated bilirubin, resulting in jaundice, thus making the neonate black and yellow. If the newborn is black and yellow, it is recommended to consult the doctor as soon as possible to clarify the diagnosis and then carry out targeted treatment.