The blackened ends of the fingers of newborn babies are often caused by poor blood circulation in the fingers, congenital heart disease, trauma, and so on. 1. Poor blood circulation in the fingers: the newborn may be wearing too tight clothes or the newborn’s fingers may be wrapped with wires, resulting in poor blood circulation, which leads to the blackened ends of the fingers, and may be accompanied by slight swelling. 2. Congenital heart disease: for example, congenital mitral stenosis, aortic ductus arteriosus, tricuspid valve and aortic valve lesions, etc., which may lead to the deterioration of the blood supply ability of the heart, resulting in the symptoms of blackened fingers, cyanosis of the lips and developmental delays. 3. Trauma: it may be due to the newborn’s finger trauma, resulting in bleeding and swelling around the joints, and the hematoma will appear after the absorption of the phenomenon of blackened and darkened skin. The darkening of the ends of the fingers of newborns may also be caused by other reasons, and it is recommended to go to the hospital in time to find out the cause.