Definition
A fever in small children is defined as a body temperature above 38°C, a high fever is understood to be temperatures above 39°C, whereby more than 41°C can be life-threatening, as it can lead to the destruction of the body’s own proteins. The normal body temperature of infants should be between 36.5 and 37.5°C. Rectal temperature measurement in babies or infants is considered the most reliable and accurate.
At 0.5°C, the fever limit is slightly lower than that of adults, for whom the term fever is only used from 38.5°C. However, fever is not a disease in itself, but a reaction of the body to a pathological event, so that it should rather be called a symptom. The aim of upregulating the body’s core temperature is to optimize the conditions for the body’s own defense processes, so that, for example, the cells and enzymes involved in the defense against bacteria and viruses can function more effectively and faster.
The control center for the body temperature regulation is the hypothalamus of the brain, which continuously measures the current actual temperature and adjusts it to the target temperature. If the hypothalamus receives the information that the immune system must be activated by certain disease conditions (such as inflammation or infection), it is therefore able to increase the body temperature and cause the baby to have a fever by activating the muscles (shivering, chills), narrowing the blood vessels and – especially only possible with small children – producing heat in the brown adipose tissue. It is important to note, however, that the body temperature can fluctuate more strongly throughout the day, especially in the youngest children, than in adults, so that not every slight rise in temperature should cause concern for the parents.
However, if the temperature increase lasts longer than 3 days, a pediatrician should be consulted as early as possible to initiate a research into the causes and therapy. However, an independent fever-lowering experiment using medication should be urgently avoided, as not all fever-lowering drugs commonly used for adults are also suitable for small children! As a rule of thumb, babies under 3 months of age should consult a pediatrician as soon as the temperature reaches >38°C, and babies over 3 months of age should consult a pediatrician as soon as the temperature reaches >39°C.
