What Is the Normal Body Temperature of an Infant?

Everyone knows that a normal human body temperature is 98.6 degrees Fahrenheit--except when it isn't. The 98.6-degree standard is nothing more than an average. "Normal" body temperature can vary from person to person and from situation to situation. For infants, the variation can be even bigger, because their small bodies cannot regulate temperature as well as adults can.

History

• In the mid-1800s, a German doctor named Carl Wunderlich took more than 1 million temperature readings from the armpits of 25,000 patients. The average of all his measurements was roughly 98.6 degrees Fahrenheit, a standard that is still followed to this day, even though there is evidence that it's not totally accurate. For instance, a 1991 University of Maryland study of 148 healthy adults between the ages of 18 and 40, the results of which were published in the "Journal of the American Medical Association" in September 1992, found the benchmark to be 98.2 degrees.

Normal Temperature

• Though studies differ, normal temperature for adults seems to fall somewhere between 98 and 99 degrees Fahrenheit. However, this is not necessarily the case for infants. According to the Canadian Paediatric Society, normal temperature for babies can range from 94.5 to 100.4, depending on the manner in which the temperature is measured. Temperature can also vary depending on time of day. It is usually lower in the morning and higher in the afternoon.

Measuring Temperature

• The Canadian Paediatric Society lists four main ways to measure temperature: rectally, orally, in the ear or under the arm. For infants, measuring temperature orally is usually not an option, and under-the-arm readings are the least accurate. The two most reliable readings come from measuring temperature rectally or in the ear. A normal rectal temperature ranges from 97.9 to 100.4, while a normal temperature measured in the ear ranges from 96.4 to 100.4.

Abnormal Temperature

• Most pediatricians agree that any temperature over 100.4 degrees is a fever. Though fever in an infant can have a benign cause, such as teething, it usually indicates illness. Conversely, a sustained rectal temperature below 97 degrees is abnormal in a newborn and could be a sign of a serious illness. An extremely low or high temperature in an infant could also be a sign of hyperthermia or hypothermia--meaning the baby's temperature is too high or too low.

Prevention/Solution

• Keeping your baby's temperature in a normal range may seem like it should be as easy as keeping him healthy. But other factors play a role. For instance, not overdressing a baby is important, but it's a mistake that many new parents make. One rule of thumb, according to the Perinatal Foundation, is to dress your baby in one more layer of clothing than you are wearing. Keep your baby's room at a comfortable temperature, and, if you take your baby outside for an extended period of time, keep him out of direct sunlight.