If a 4-month-old baby’s body temperature is 37.1°C, it is generally normal because the body’s temperature is only feverish if it exceeds 37.2°C, and anything below 37.2°C is normal. The vast majority of infants and children’s body temperature does not reach 37.1℃, basically hovering between 36.5-36.9℃. If the temperature reaches 37.1℃, it is recommended to closely observe the baby’s symptoms. You can take the temperature 3 times a day, in the morning, at noon and at night, to observe the change of temperature. If the temperature is below 37.2℃ for 3 times in a day, it is normal and there is no need to worry too much. If the temperature exceeds 37.2℃ in a short period of time, it is likely to be feverish and should be checked by the hospital promptly. If the fever is low for a long time, you need to identify the cause and then carry out symptomatic treatment to avoid delaying the disease.