Pediatric fever is one of the most common signs or symptoms in infants and children. Parents are anxious and nervous about this, especially if it is the first time a baby has a fever. When a baby has a fever, the clinician often recommends a routine blood test. Parents don’t understand when their baby has a fever – they just had it checked last time, so why do it again? Most of the fevers in babies are colds, also called “upper respiratory tract infections”, and more than 90% of the pathogens are viruses, which are treated without antibiotics. There are also bacterial causes. The identification methods are: blood tests and CRP (C-reactive protein – an indicator of inflammation, mostly bacterial infections when elevated: rheumatism, rheumatoid, tumors, etc. can also be elevated) monitoring. After the test, the baby can be given reasonable medication according to the situation. Avoid unreasonable use of antibiotics. If the white blood cells are around 10,000, or within 10,000, not less than 5,000, neutrophils are not high, generally only antiviral drugs and antipyretic drugs can be used, if close to 15,000, neutrophils are also high, generally add antibacterial drugs, if the resistance is low, or often infusion, or white blood cells are higher than 15,000, it is generally recommended that the infusion is up, using antibacterial drugs. There are also people, based on experience, below 38.5 °, can be combined with pharyngeal congestion, temporarily do not check the blood routine. It can be considered! But there are some babies, although, the body temperature is not too high, blood tests, white blood cells, (WBC) is very high.