How to Accurately Measure Baby’s Body Temperature?

How to Accurately Measure Babys Body Temperature

Newborn babies have quite limited ways to express how they are feeling. It becomes quite daunting for parents to learn what is troubling their child. You can observe changes in the baby’s health by monitoring his body temperature. Learn different ways of taking body temperature to prevent the baby against several health issues.  

What Are Different Methods of Taking Body Temperature?

You can choose one of the following methods to measure your baby’s body temperature:

Oral measurement method: You will need a thermometer to test your baby’s body temperature. First, disinfect the device by using 75% alcohol and then wash it with clean water. Place that thermometer under your baby’s tongue and then close his mouth tightly. Keep the thermometer as it is for the next five minutes. Now, check the reading. Your baby is fine if you get the reading between 36.3 to 37.2°C.

Axillary measurement method: There is no risk of cross infection when you take the body temperature through this method. Therefore, it has become one of the most commonly used methods to measure body temperature.

You should first wipe your baby’s body armpits to clean the sweat. Now, place the mercury end of your thermometer in the armpit. Make sure half of the thermometer is covered with your baby’s arm. Keep it as it is for the next 5-10 minutes. If you get 36-37°C reading on the thermometer, your baby’s body temperature is normal.

Anal temperature test: It is a widely chosen method to measure body temperature of comatose patients or children. The patient would lie on the bed in the supine position. Now, the doctor will lubricate the upper body of the thermometer. It will be half inserted into the anus and kept there for the next three minutes. The doctor will take the reading and the patient is fine if the reading shows values between 36.5°C and 37.7°C.  

What Precautions You Should Take When Measuring Body Temperature?

You should take the following precautions when measuring the body temperature:

  • Check all the values given on the thermometer before you check the body temperature. Shake this instrument perfectly to get the zero value on the thermometer. Do not place it in hot water to clean it because its reading will increase. You won’t get the right body temperature in this way.
  • You should not put thermometer in an infant’s or young child’s mouth to take his body temperature.
  • If you are measuring the body temperature orally, let the patient eat or drink something before that. Wait for the next 30 minutes and then measure the body temperature.
  • You should take a specialist’s help to measure an infant or young child’s temperature. Ask a nurse or doctor for service to avoid potential accidents.
  • If you are getting an inconsistent temperature value on the thermometer, you should measure it again to get accurate value. Thus, you will measure accurate body temperature of the patient.

How to Measure Temperature of Five Major Body Parts?

External environment factors do not affect the body temperature easily. The surface temperature of a person’s body may change due to the changes in exterior temperature. It will not affect the internal temperature of a person’s body. Therefore, it is quite important to measure the baby’s body temperature accurately to diagnose fever.

Doctors commonly use ear probe, armpit probe, mouth probe, and liver probe methods to measure body temperature. However, you can also touch the baby’s forehead to know whether he has fever or not. It can be a false alarm and therefore you should follow an accurate method.

Your baby’s body temperature will rise if he has fever. The brain receives blood from carotid artery, which is responsible for regulating body temperature. Eardrum, armpit, and space below the tongue are the closest organs to this temperature control center. Therefore, the doctor checks temperature in these parts of the body to get accurate readings on a thermometer.  

1. Oral Temperature Measuring Method

You can use two types of thermometers to measure body temperature of a baby orally, which are:

Mercury thermometer

It is suitable for kids 3 years of age or older. The body temperature will affect mercury’s volume. Thus, you will get an accurate value on the thermometer as you put it in the baby’s mouth. Make sure the baby doesn’t bite the thermometer!

Method: Sterilize the thermometer before you put it in your baby’s mouth. Now, shake it gently to get the reading below 37°C. Place the thermometer gently under your baby’s tongue and keep it there for the next three minutes. Now, take it out and check the reading.

Your baby is suffering from fever if the temperature reading goes above 37.5°C!

Electronic thermometer

Sterilize the thermometer and then put it under your child’s tongue. Wait for the next 1 minute and the instrument will make a beep. Take it out and check the reading. It is more prone to show a false reading than mercury thermometer. Therefore, you should check multiple times to ensure the reading is accurate.

Measuring body temperature through the ear: You can try this method if your baby is older than 1 month. The instrument used in this method throws infrared rays towards the eardrum to calculate the temperature. It is a fast and easy way of measuring body temperature.

This method works only if the position of eardrum is aligned. You will get false readings if there is earwax or the instrument is not positioned perfectly.

Method: Hold and pull back the cochlea slightly back. Newborn babies do not have ear canals straight till the eardrums. Therefore, you can create a safe passage by pulling cochlea. Now, hold the instrument near the ear and click the button to throw the infrared rays.

The temperature measuring instrument will display temperature readings on the screen. You must repeat this method at least three times to ensure the reading is accurate. If you get temperature value above 37.5°C, the baby is suffering from fever.

2. Measuring Body Temperature Through Forehead

This method is also quite easy and suitable for babies 1 month old or older. An infrared thermometer will scan the forehead and display temperature reading on the screen. This method is a fast, convenient, and hassle-free alternative to other time-consuming methods.

You may get false reading sometimes because the outer temperature can affect the baby’s skin temperature. So, beware of that issue!

Method: Put on plastic gloves before you begin the process. Now, pick the infrared thermometer and hold it above your baby’s forehead. Press the button and direct the infrared rays between the baby’s eyes. Now, move the thermometer left and right for a minute.

Check the readings appearing on the screen. The instrument is working perfectly if you are getting the same reading. It will allow you to check the baby’s accurate body temperature within a few seconds!

3. Axillary Exploration Method

You can try a mercury thermometer or an electronic thermometer to check body temperature. The first method is suitable for newborn babies and it shows the most accurate results. However, it might cause a bit discomfort to the baby!

The method is more suitable for toddlers and children older than 3 years. It is fast, easy, and much safer for children. The baby might feel a bit uncomfortable because you will put the thermometer in his armpit!

Let’s check both methods:

Method 1: Mercury thermometer

Sterilize the thermometer and then shake it for a few seconds. Get the reading below 37°C and then put it between your baby’s feet or under the armpit for 3 minutes. The baby might feel a bit uncomfortable, but you shouldn’t remove the thermometer. Check the reading after three minutes to measure your baby’s body temperature.

Method 2: Electronic thermometer

Put on clean gloves and then dip a cotton ball in alcohol. Use that alcohol soaked cotton ball to sterilize the thermometer. Now, put this thermometer under your baby’s armpit and keep it there for one minute. Take the body temperature measuring instrument out and check the reading.

If you get body temperature reading above 37.5°C, your baby has fever and you must take him to the doctor!

4. Rectal method

You can choose a mercury or electronic thermometer to measure the temperature. Sterilize the thermometer and then clean it with a clean wet cloth. Now, apply some lubrication and then put the thermometer 1.5cm in the rectum.

Keep the instrument in rectum for 3 minutes if it’s a mercury thermometer. Remove it after 1 minute if it’s an electronic thermometer. Check the value shown by the thermometer. Take the baby to the doctor if the value is above normal body temperature.

When Your Baby Is Suffering From Fever?

Check what different thermometer readings reveal to know when your baby is suffering from fever.

  • 37.5-38°C is normal body temperature
  • 38.1-39°C is moderate fever
  • 39.1-41℃ reading shows high fever
  • Your baby needs immediate medical attention if his body temperature is above 41℃!


Now you know different ways to measure body temperature of a baby. Choose an appropriate method and the best thermometer to measure your baby’s body temperature at home. Provide the best treatment if your baby’s body temperature is higher than what it should be!

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