How to Check a Baby’s Temperature | Best Practices

How to Check a Baby’s Temperature | Methods, Accuracy, and Best Practices

When your baby seems unwell, one of the first things you’ll likely want to do is check their temperature. I remember how nervous I was the first time I had to check my baby’s temperature, not knowing the best method to get an accurate reading. So, how do you check a baby’s temperature accurately? The best method depends on the baby’s age, but the rectal method is generally considered the gold standard for newborns and infants. Other options, like armpit and forehead readings, can also provide reliable results if done correctly. 

In this guide, we’ll explore the different methods for checking a baby’s temperature, how to use them effectively, and when to seek medical attention.

The Most Accurate Methods for Checking a Baby’s Temperature

There are several ways to check a baby’s temperature, but some methods are more accurate than others. Digital thermometers are widely recommended for their ease of use and reliability, but the placement of the thermometer (rectal, armpit, forehead) will affect the accuracy.

1. Rectal Temperature (Most Accurate)

For babies under 3 months old, checking the temperature rectally is considered the most accurate method. This involves gently inserting a digital thermometer into your baby’s rectum to get an internal temperature reading.

• Why It’s Accurate: Rectal temperature measures the baby’s core body temperature, which is the most reliable indicator of fever in newborns and infants.
• Tip: Always lubricate the tip of the thermometer with petroleum jelly to make insertion easier and more comfortable for the baby.

2. Armpit (Axillary) Temperature

Taking a baby’s temperature in the armpit (axillary) is another common method, particularly for babies who are less than 3 months old or when a rectal temperature is difficult to obtain. This method is less invasive but slightly less accurate than rectal temperature.

• Why It’s Used: The axillary method is easier and more comfortable for the baby, but it can underestimate the baby’s core temperature. It’s typically used as a quick screening before confirming with another method.
• Tip: Ensure the thermometer is pressed firmly under the baby’s arm and that the baby’s arm is held down securely to get the best reading.

3. Forehead (Temporal) Temperature

Forehead thermometers (temporal artery thermometers) are becoming increasingly popular for their convenience and non-invasive approach. These thermometers use infrared technology to measure the temperature of the temporal artery in the forehead.

• Why It’s Used: Forehead thermometers are quick and easy, making them ideal for checking a baby’s temperature while they’re asleep or fussy. They are less accurate than rectal thermometers for babies under 3 months old but are useful for older babies and children.
• Tip: Ensure the forehead is dry and clean before using a temporal thermometer, as sweat can interfere with the accuracy of the reading.

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Table 1: Comparison of Baby Temperature Methods

Temperature Method	Accuracy	Best for Which Age	Key Consideration
Rectal (Digital)	Most accurate for core body temperature	Best for newborns and infants (under 3 months)	Can be uncomfortable, requires careful handling
Armpit (Axillary)	Less accurate than rectal	Suitable for all ages, but confirm with rectal	Easier but can underestimate body temperature
Forehead (Temporal)	Convenient but less accurate in younger infants	Best for babies over 3 months	Quick and non-invasive, less reliable for newborns

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How to Properly Use a Thermometer on a Baby

Using a thermometer properly is key to getting an accurate reading. Whether you’re using a rectal thermometer, an armpit thermometer, or a forehead thermometer, it’s important to follow the right technique.

1. Taking a Rectal Temperature

To take your baby’s temperature rectally, follow these steps carefully:

• Step 1: Wash the thermometer with soap and water, then rinse it with cool water.
• Step 2: Apply a small amount of petroleum jelly to the tip of the thermometer to make insertion easier.
• Step 3: Place your baby on their back with their knees bent, or lay them on their stomach over your lap.
• Step 4: Gently insert the thermometer about 1/2 to 1 inch into the baby’s rectum.
• Step 5: Hold the thermometer in place for the time specified by the manufacturer (usually around 30 seconds to a minute).
• Step 6: Remove the thermometer, read the temperature, and clean the thermometer thoroughly.
• Tip: Always comfort your baby during and after the process, as rectal temperatures can be uncomfortable.

2. Taking an Armpit (Axillary) Temperature

To take an armpit temperature, follow these steps:

• Step 1: Make sure the baby’s armpit is dry.
• Step 2: Place the thermometer’s tip in the center of the baby’s armpit.
• Step 3: Hold the baby’s arm snugly against their body to ensure the thermometer stays in place.
• Step 4: Wait for the thermometer to beep or show that it’s finished reading (usually around a minute).
• Step 5: Read the temperature and, if needed, confirm with a more accurate method like rectal temperature.
• Tip: Armpit temperatures are generally lower than rectal temperatures, so you may need to add about 1°F to the reading for accuracy.

3. Using a Forehead (Temporal) Thermometer

Forehead thermometers are easy to use, but it’s important to follow the right steps for accuracy:

• Step 1: Make sure your baby’s forehead is clean and dry.
• Step 2: Place the thermometer against the baby’s forehead, following the manufacturer’s instructions.
• Step 3: Move the thermometer across the forehead or place it at a specific point, depending on the type of device.
• Step 4: Wait for the reading and note the temperature.
• Tip: For the most accurate result, avoid using a forehead thermometer if your baby is sweating or just came from a warm or cold environment.

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Table 2: Step-by-Step Guide to Taking a Baby’s Temperature

Method	Step-by-Step Process	Key Tips
Rectal (Digital)	1. Wash and lubricate the thermometer 2. Insert gently 1/2 inch into rectum 3. Hold for required time 4. Clean thermometer thoroughly	Always be gentle and comfort the baby
Armpit (Axillary)	1. Place thermometer in dry armpit 2. Hold arm down snugly 3. Wait for reading	Add 1°F to the reading for accuracy
Forehead (Temporal)	1. Clean forehead 2. Scan or place thermometer as instructed 3. Wait for reading	Avoid use if baby’s forehead is sweaty

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Understanding Normal Baby Temperature Ranges

Knowing what temperature is considered normal for your baby is essential for identifying fevers. While each baby is different, there are general temperature ranges that can help guide your decision on when to seek medical attention.

1. Normal Temperature Ranges

For babies, normal body temperature typically falls between 97°F (36.1°C) and 100.4°F (38°C). Anything above this range is generally considered a fever, which may indicate an infection or illness.

• Rectal temperature: 98.6°F to 100.4°F (37°C to 38°C) is normal.
• Armpit temperature: 97°F to 99°F (36.1°C to 37.2°C) is normal.
• Forehead temperature: 97.5°F to 100.3°F (36.4°C to 37.9°C) is normal.
• Tip: Temperatures can vary slightly depending on the method used, so always account for minor differences when comparing readings.

2. When to Consider It a Fever

A fever in a baby is typically defined as a rectal temperature of 100.4°F (38°C) or higher. Fevers are a sign that the body is fighting an infection, but they can also be caused by overheating, vaccinations, or other non-serious factors.

• Tip: For babies under 3 months old, a fever of 100.4°F (38°C) or higher requires immediate medical attention.

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Table 3: Normal Temperature Ranges for Babies

Method	Normal Temperature Range	Fever Threshold
Rectal (Digital)	98.6°F to 100.4°F (37°C to 38°C)	100.4°F (38°C) or higher
Armpit (Axillary)	97°F to 99°F (36.1°C to 37.2°C)	99°F (37.2°C) or higher
Forehead (Temporal)	97.5°F to 100.3°F (36.4°C to 37.9°C)	100.4°F (38°C) or higher

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When to Seek Medical Attention for a Baby’s Fever

While fevers are common and often harmless, there are certain situations where you should seek medical help immediately. It’s important to monitor your baby’s behavior and overall health in addition to their temperature.

1. Fevers in Newborns Under 3 Months

For newborns under 3 months old, any fever over 100.4°F (38°C) is considered an emergency. Since young babies have underdeveloped immune systems, even a mild fever can indicate a serious infection.

• Tip: Contact your pediatrician or visit the emergency room immediately if your newborn has a fever over 100.4°F.

2. Prolonged or High Fevers

If your baby’s fever lasts more than 24 hours or reaches 102°F (38.9°C) or higher, it’s essential to contact your healthcare provider. High fevers, especially when persistent, can be a sign of a more serious illness.

• Tip: Keep track of your baby’s fever duration and intensity, as this information will help your doctor assess the situation.

3. Other Concerning Symptoms

In addition to fever, if your baby is showing other concerning symptoms such as lethargy, trouble breathing, excessive crying, or difficulty feeding, it’s crucial to seek medical attention. These symptoms, combined with fever, can indicate a more serious condition.

• Tip: Always trust your instincts—if your baby seems unusually unwell, don’t hesitate to call your pediatrician.

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FAQs – How to Check a Baby’s Temperature

What is the best way to check a newborn’s temperature?

The best way to check a newborn’s temperature is with a digital rectal thermometer, as it provides the most accurate reading of core body temperature.

Can I use a forehead thermometer on a baby?

Yes, you can use a forehead (temporal) thermometer on a baby, but it’s less accurate for newborns. It’s better suited for babies over 3 months old.

How often should I check my baby’s temperature?

You should check your baby’s temperature if they seem unwell, are showing signs of fever, or have other concerning symptoms. There’s no need to check it regularly unless advised by a doctor.

What is considered a fever for a baby?

A fever in a baby is typically defined as a rectal temperature of 100.4°F (38°C) or higher. For babies under 3 months, a fever over 100.4°F is an emergency.

Can I use an ear thermometer for my baby?

Ear thermometers are generally not recommended for newborns and infants under 6 months, as their ear canals are too small for accurate readings.

Should I add a degree to my baby’s armpit temperature?

Yes, armpit (axillary) temperatures tend to be lower, so you may need to add about 1°F to the reading for accuracy.

Is a digital thermometer safe for babies?

Yes, digital thermometers are safe and highly recommended for babies. They are easy to use and provide quick, accurate readings.

What should I do if my baby’s temperature is too low?

If your baby’s temperature is below 97°F (36.1°C), it may indicate hypothermia, especially in newborns. Dress your baby warmly and contact your doctor immediately if their temperature stays low.

How can I comfort my baby during temperature checks?

To comfort your baby during temperature checks, speak to them softly, hold them securely, and try to make the process as quick and gentle as possible.

When should I call the doctor about my baby’s temperature?

You should call the doctor if your baby is under 3 months old and has a fever over 100.4°F, if their fever lasts more than 24 hours, or if they show other concerning symptoms like lethargy, difficulty breathing, or refusal to eat.

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Conclusion: How to Check a Baby’s Temperature

Ensuring Accurate Readings and Knowing When to Seek Help

Checking your baby’s temperature is a key skill for every parent, and knowing which method to use can make all the difference in getting accurate results. Rectal temperatures provide the most reliable reading for newborns, while armpit and forehead methods are good alternatives for older babies. Understanding normal temperature ranges and when a fever becomes a concern will help you respond appropriately to your baby’s needs. Always consult your pediatrician if your baby’s temperature is unusually high or low, or if they show other worrying symptoms alongside a fever.