If you find that the baby nails black, mostly consider two reasons, the first reason, you can consider whether there is trauma, if the baby’s fingers, accidentally extruded by external forces, which may lead to bruising under the nail bed, then the nails will appear black. The second reason, consider because the body has a lack of oxygen, local blood circulation is poor, can also lead to extremity endings, and the lips and mouth part of the bruising, black, may be related to heart disease. Should be observed through the baby’s state, to analyze what exactly is the cause of, if for trauma, the baby finger will have a painful feeling, it is recommended to go to the surgical consultation, if necessary, nail extraction treatment. If it is caused by lack of oxygen, you should pay attention to the baby’s lips and mouth area whether there is a concomitant bruising, as well as the respiratory status, oxygen saturation test or cardiac ultrasound examination.