Learning About Taking Your Baby's Temperature

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Taking a baby's rectal temperature

What is body temperature?

Body temperature is a measure of how well your baby's body can make and get rid of heat. You can find out what your baby's temperature is by using a thermometer. There are specific types of thermometers to use in different parts of the body.

A rectal or ear temperature reading is about 0.5°F (0.3°C) to 1°F (0.6°C) higher than an oral (mouth) reading. A temperature taken in the armpit is about 0.5°F (0.3°C) to 1°F (0.6°C) lower than an oral temperature reading. Rectal temperatures are thought to be the most accurate way to check a baby's temperature.

Experts say that a rectal temperature in a baby over 100.4°F (38°C) is a fever.

The method you use to take a baby's temperature depends on the baby's age:

  • For a baby age 0 to 3 months, it's best to use a rectal thermometer only.
  • For a child age 3 months to 3 years, you can use a rectal, armpit, or ear thermometer. But rectal is best.

How do you take your baby's rectal temperature?

This is the most accurate way to measure body temperature. It is recommended for babies.

  1. Put a lubricant jelly or petroleum jelly, such as Vaseline, on the tip of the thermometer.

    This will help you insert it easily.

  2. Choose a quiet place so that the baby won't be distracted or move around too much.
    1. Place your baby faceup with legs bent toward the chest. Place your hand on the back of the thighs or holding the feet as if you were changing a diaper.
    2. Or place your baby facedown on your lap or on a flat surface that's covered or padded, such as a bed.
  3. Insert the thermometer.
    1. Spread the baby's buttocks apart with one hand.
    2. Gently insert the tip end of the rectal thermometer about ½ in. (1.25 cm) to 1 in. (2.5 cm) inch into the rectum. Don't force it.
    3. Hold the thermometer in place with two fingers close to the rectum (not near the end of the thermometer).
  4. Leave the thermometer in place for the required amount of time.

    Some digital thermometers give a series of short beeps when the reading is done. Or you can time yourself with a watch or clock.

  5. Remove the thermometer and read it.
  6. Clean the thermometer with cool, soapy water, and rinse it off before putting it away.

After a thermometer has been used to take a rectal temperature, don't use it to take an oral temperature.

How do you take your baby's ear temperature?

Ear temperatures aren't as accurate as rectal temperatures. Don't use ear probe thermometers on babies younger than 3 months.

  1. Check that the ear probe is clean.

    If it's dirty, wipe it gently with a clean cloth. Don't put the thermometer in water.

  2. To keep the probe clean, use a disposable probe cover.

    Use a new probe cover each time you take an ear temperature. Attach the disposable cover to the probe.

  3. Turn the thermometer on.
  4. Pull your baby's earlobe back.

    This will help place the probe in the ear canal.

  5. Center the probe tip in your baby's ear, and push gently inward toward the eardrum.
  6. Press the "on" button to display the temperature reading.
  7. Remove the thermometer.
  8. Throw away the used probe cover.

How do you take your baby's armpit temperature?

An armpit temperature is not as accurate as a rectal temperature.

  1. Place the thermometer under the arm, with the tip in the center of your baby's armpit.
  2. Press your baby's arm against his or her body.
  3. Leave the thermometer there for as long as the instructions say.
  4. Remove the thermometer and read it.
  5. Clean the thermometer with cool, soapy water.

    Rinse it off before you put it away.

Where can you learn more?

Go to http://www.healthwise.net/patientEd

Enter D448 in the search box to learn more about "Learning About Taking Your Baby's Temperature".

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