The causes of high leukocytes in babies may be bacterial infections, viral or mycoplasma infections, malignant neoplastic diseases and so on. 1. Bacterial infections: for example, lobar pneumonia, acute glomerulonephritis, etc., are bacterial infections, which will cause white blood cells to rise, accompanied by neutrophil elevation. 2. Viral or mycoplasma infections: for example, most of the upper respiratory tract infections are caused by viral infections, and the leukocytes will be increased, accompanied by lymphocytes and monocytes; mycoplasma pneumonia will also be elevated, but there is no specificity. 3. Malignant neoplastic diseases: such as leukemia or lymphoma. It is recommended that babies with elevated white blood cells consult a hospital to clarify the cause and then treat it.