Baby hand back black may be related to physiological factors such as outdoor activities, pathological factors such as lack of vitamin E or C, etc.. 1. Physiological factors: baby hand back black is generally normal physiological phenomenon, at this time first look at the baby whether the outdoor activities or do not do a good job of sunscreen measures; if the parents are darker may also be caused by heredity. 2. Pathological factors: baby hand back black may also be related to the lack of vitamin E or vitamin C, when the body lacks such vitamins may also lead to black skin, because vitamins can improve the skin’s antioxidant capacity. In addition, diseases can also lead to darker skin, such as liver dysfunction, skin pigmentation and so on. As you can see, if your baby is only very dark occasionally due to outdoor activities, there is usually no need to deal with it, but if it is very serious or remains unrelieved, it is recommended to seek medical treatment.