Baby fever only upper body fever how to return a responsibility

When a child has a fever, only the upper body is hot. This should be related to the regulation of sympathetic and parasympathetic nerves in the child's body. Of course, it is also related to the external temperature. You can use a thermometer to measure the child's temperature. If the body temperature is higher than 38.5 degrees, It can be treated with oral ibuprofen.