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Measuring a Baby's Temperature

Where should a baby's temperature be taken?

Today's digital thermometers make taking a baby's temperature simple, with quick results. For best results in babies and toddlers up to 3 years of age, the American Academy of Pediatrics recommends taking the temperature rectally, by placing a thermometer in the baby's anus. This method is accurate and gives a quick reading of the baby's internal temperature. Axillary (underarm) temperature measurements may be used for babies ages 3 months and older. Other types of thermometers, such as tympanic (ear) type thermometers, may not be accurate for newborns and require careful positioning to get a precise reading. Skin strips that are pressed on the skin to measure temperature are not recommended for babies. Touching a baby's skin can let you know if he or she is warm or cool, but you cannot measure body temperature simply by touch.

A new type of thermometer, called temporal artery thermometry, is almost as accurate as a rectal thermometer with less discomfort and less disturbing to a newborn.

Preparing the thermometer

There are different instructions depending on which type of thermometer you are using to take your baby's temperature. Be sure to follow the instructions for each carefully.

  • Electronic digital thermometers:

    • Place a disposable sheath over the thermometer.

    • Zero or reset the thermometer.

    • Lubricate the insertion end with a water-soluble lubricant.

  • Glass thermometers:

    • Check the thermometer carefully for cracks or splinters. If broken, do not use.

    • Disinfect the thermometer with rubbing alcohol or an antiseptic solution.

    • Rinse well in cool, not hot water.

    • Hold the thermometer on the opposite end of the bulb between your thumb and fingers.

    • Hold the thermometer just below your eye level to read it.

    • Roll the thermometer until you can see the line inside the glass.

    • Make sure the temperature reads below 96° F.

    • If the reading is higher, use quick, whip-like movements of your wrist to shake the line down.

    • Shake over a bed or carpet. This helps prevent the thermometer from breaking if you accidentally drop it while shaking it.

    • Lubricate the thermometer bulb with a water-soluble lubricant or petroleum jelly.

About glass thermometers containing mercury

Do not use glass thermometers containing mercury. According to the EPA, mercury is a toxic substance that poses a threat to the health of humans, as well as to the environment. Because of the risk of breaking, glass thermometers containing mercury should be removed from use and disposed of properly in accordance with local, state, and federal laws. Contact your local health department, waste disposal authority, or fire department for information on how to properly dispose of mercury thermometers.

Taking the baby's rectal temperature

Oral and rectal glass thermometers have different shapes and one should not be substituted for the other. Do not use oral thermometers rectally as these can cause injury. Rectal thermometers have a security bulb designed specifically for safely taking rectal temperatures.

  • Place the baby across your lap or changing table, on his or her abdomen, facing down. Place your hand nearest the baby's head on his or her lower back and separate the baby's buttocks with your thumb and forefinger.

  • Using your other hand, gently insert the lubricated bulb end of the thermometer one-half to one inch, or just past the anal sphincter muscle.

  • The thermometer should be pointed towards the child's navel.

  • Hold the thermometer with one hand on the baby's buttocks so the thermometer will move with the baby. Use the other hand to comfort the baby and prevent moving.

  • Never leave a baby unattended with a rectal thermometer inserted. Movement or a change in position can cause the thermometer to break.

  • Hold thermometer for at least 1 minute or until an electronic thermometer beeps or signals.

  • Remove the thermometer.

  • Wipe the bulb.

  • Read immediately and record.

  • Disinfect the thermometer with rubbing alcohol or an antiseptic solution.

If a baby's temperature is 100.4° F or higher, make sure he or she is not dressed too warmly or over bundled with blankets. Crying may also raise a baby's temperature. Retake the baby's temperature again in about 30 minutes. If the temperature is still high, call your baby's doctor immediately.