The main reasons why babies have veins on forehead include the following: 1, normal physiological phenomenon, because some children’s subcutaneous fat is very thin, especially in this part of the forehead, and the so-called veins refer to the veins, children due to less subcutaneous fat, easy to see the appearance of veins, especially when the child is crying more obvious, as long as the child does not have obvious poor milk consumption, vomiting, fever, etc., no need to deal with. 2, children suffering from hyperthyroidism and other pathological factors, after children suffering from hyperthyroidism will cause an increase in metabolic rate, children’s heart rate accelerated, forehead tend to be more prominent, we should do thyroid function in time to confirm the diagnosis.