Hypothermia is defined as a baby’s axillary temperature of 37.5-38 degrees. The normal body temperature of babies is: axillary temperature 36-37 degrees; anal temperature is normally 36.5-37.5 degrees, the anal temperature can best reflect the real temperature of the baby’s body, but because the axillary temperature is convenient to measure, it is easily accepted by everyone. Fever is defined as an axillary temperature ≥ 37.5 degrees or an anal temperature ≥ 38 degrees, and fluctuations of more than 1 degree within 1 day is called fever. The degree of fever is usually judged according to the axillary temperature. Low fever refers to axillary temperature <38 degrees; medium fever refers to axillary temperature between 38-39 degrees; axillary temperature >39 degrees and <41 degrees is high fever; >41 degrees is super high fever.