They must also be able to understand that they cannot bite down on the thermometer. Most children are not ready for this oral temperature-taking until age four or five. One pacifier thermometer even plays a lullaby whenever fever is detected. In fact, many pediatricians consider rectal readings the gold standard of temperature-taking. Like oral models, rectal thermometers are available in both mercury-glass and digital models.
Rectal readings are usually one degree higher than temperatures taken orally.
The underarm is the least invasive site for temperature-taking. Underarm readings are usually one degree lower than temperatures taken orally. The most advanced electronic models make this conversion automatically. These sophisticated underarm thermometers employ advanced infrared technology to take a succession of rapid readings. They then utilize an internal computer to calculate body temperature with a level of speed and accuracy that is unavailable with other devices.