1. What is low-grade fever in babies? Low-grade fever in babies refers to a slight fever with a body temperature between 37.5°C and 38°C, which usually does not cause obvious discomfort. This condition is relatively common in infants and young children. In most cases, it is caused by colds, upper respiratory tract infections, etc. 2. How to identify low-grade fever in babies? A low-grade fever in a baby usually does not have obvious symptoms, but if you notice the following, it may mean that your child is experiencing a low-grade fever: 1. A parent touches the child