The blackening of the nail roots of newborns may be due to factors such as exposure to cold, discoloration of clothing, congenital heart disease, etc. Warmth, cleanliness and surgical treatment may be given to alleviate the situation. 1. Cold factor: For newborns, if they are in a low-temperature environment for a long time, the blood circulation in the peripheral nerves of the limbs may slow down due to cold, and the black color of the nail roots will appear, mainly due to cold, and they need to get out of the undesirable environment in time and give warm treatment. 2. Decolorization of clothing: If the newborn is wearing dark-colored clothing, the nail roots may be stained due to the decolorization of clothing, which needs to be cleaned in time. 3. Congenital heart disease: If the newborn has congenital heart disease, it may be due to the lack of oxygen content in the body, and there will be cyanosis, nail bruising and other related symptoms, according to the actual situation of the child, if necessary, to give the surgical way of treatment. There may also be other reasons for the blackening of the roots of the nails in newborns, so if necessary, cooperate with the doctor to do further tests to determine the cause before treatment.