Greening around the mouth in infants may be caused by congenital heart disease, lung disease, etc. It may also be physiologic. 1. Congenital heart disease: for example, larger ventricular septal defects, tetralogy of Fallot, etc., which often leads to a decrease in blood oxygen levels, and some children may develop blue around the lips. 2. Lung diseases: for example, obstructive lung disease, congenital bronchus, and pulmonary dysplasia can lead to a decrease in blood oxygen saturation, which can lead to cyanosis around the mouth. 3. Physiological factors: some babies, due to their own reasons, the skin color is relatively white, the capillaries around the mouth are more abundant, may appear around the mouth green physiological phenomenon. Babies around the mouth green may also have other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.