Newborn Fever: What’s Normal & When Parents Should Worry

Caring for a newborn can be overwhelming, especially when your baby feels warmer than usual or seems uncomfortable. One of the most common concerns among new parents is fever. It can be frightening, but understanding what is normal and what requires medical attention can help you stay calm and make the right decisions.

This guide breaks down everything in a simple, parent-friendly way — what counts as a fever, common causes, home observations you can safely make, and when it may be time to seek help.

What Is Considered a Fever in Newborns?

For newborns and babies under 3 months, a fever is generally defined as:

A rectal temperature of 38°C (100.4°F) or higher.

Rectal readings are the most reliable for newborns because ear, forehead, and armpit readings can be inaccurate at this age.

Why Fever Happens in Newborns

Not all fevers mean something is seriously wrong. Fever is the body's natural response to many things, including:

1. Viral infections

These are the most common cause. Babies can catch mild viruses easily from adults or siblings through close contact.

2. Overheating

Too many layers of clothing, heavy blankets, or a hot room can raise a baby’s temperature without an infection.

3. Immunizations

A mild fever for 24–48 hours after vaccinations is common and usually settles on its own.

4. Dehydration

Poor feeding, vomiting, or diarrhea can lead to mild temperature changes as the body struggles with fluid loss.

5. Normal fluctuations

Newborns can’t regulate body temperature as well as older children, so small variations during the day are normal.

Signs Your Baby Might Have a Fever

Besides measuring temperature, you may notice:

• Warm or hot chest and back (hands and feet can be cooler)
• Increased fussiness or irritability
• Unusual sleepiness or difficulty waking
• Poor feeding or refusing feeds
• Crying more than usual
• Fewer wet diapers than normal
• Difficulty settling or appearing uncomfortable

How to Check Your Baby’s Temperature Safely

For newborns, rectal temperature is the most accurate. General steps:

1. Use a digital thermometer.
2. Clean the tip and apply a small amount of lubricant.
3. Lay your baby on their back or tummy with legs gently lifted.
4. Insert the thermometer tip gently into the rectum (about 1–1.5 cm).
5. Hold it in place until it beeps, then read the temperature.

If the reading shows 38°C or higher in a baby under 3 months, this is considered a fever and should be taken seriously.

Home Observations You Can Make

1. Clothing and environment

Check if your baby is overdressed. Remove extra layers and use light clothing in a cool, comfortable room.

2. Feeding habits

If your baby is feeding well and swallowing normally, it is usually reassuring. Poor feeding or refusing feeds can be a warning sign.

3. Diaper output

Most newborns have at least 4–6 wet diapers per day. Fewer wet diapers may suggest dehydration.

4. Alertness

A baby who wakes up, looks around, and responds to your voice is usually doing better than one who is very floppy, drowsy, or difficult to arouse.

5. Breathing

Watch for unusually fast breathing, flaring nostrils, grunting sounds, or the skin pulling in between the ribs.

When Fever Is Likely Mild

In some situations, a mild, short-lived fever may be less concerning, for example when:

• Your baby just had vaccinations and has a slightly raised temperature.
• Your baby was overdressed or in a hot environment and cools down after layers are removed.
• Your baby has a mild flu-like illness but is still feeding, waking, and having normal wet diapers.

Even then, newborns are more fragile than older children, so close observation is still important.

When You Should Watch More Closely

Pay closer attention and consider getting advice if your baby:

• Is less interested in feeding or takes much less than usual
• Has fewer wet diapers over 12–24 hours
• Seems unusually sleepy or floppy
• Cries in a weak or unusual way
• Develops a new rash
• Breathes faster than usual or seems to struggle to breathe
• Has a fever that doesn’t improve at all over time

When to Seek Medical Care

For babies under 3 months, a rectal temperature of 38°C (100.4°F) or higher is a reason to seek medical attention.

You should also seek help if:

• Your baby is very difficult to wake or unusually quiet
• Your baby refuses to feed for several feeds in a row
• Your baby has repeated vomiting or diarrhea
• You notice seizures or unusual jerking movements
• Your baby has a fever for more than 24 hours without improvement
• Your baby seems to be in obvious pain or distress

Trust your instincts. If something feels “not right,” it is always acceptable to seek professional advice.

Safe Things You Can Do at Home

While you monitor your baby, you can:

• Dress your baby in light, breathable clothing
• Keep the room cool and well-ventilated
• Offer feeds more frequently to maintain hydration
• Use a lukewarm sponge bath to gently cool the skin (no cold water)
• Let your baby rest and avoid overstimulation
• Hold and comfort your baby to help them feel secure

Do not give fever medicine to a newborn unless advised by a healthcare professional.

What You Should NOT Do

• Do not use cold baths, ice packs, or very cold cloths
• Do not rub the baby with alcohol or other strong substances
• Do not overdress or wrap your baby in thick blankets
• Do not give any medicine without guidance
• Do not ignore persistent high fever or worrying symptoms

Why Fever Can Be More Serious in Newborns

Newborns have immature immune systems and cannot fight infections as effectively as older children. They also become dehydrated more quickly and may not show clear symptoms. That is why even a single fever in a very young baby deserves careful attention.

How to Help Reduce the Risk of Fever in Newborns

• Wash your hands before handling the baby
• Limit close contact with people who are unwell
• Keep the home environment clean and smoke-free
• Avoid overdressing your baby indoors
• Ensure your baby is feeding regularly and gaining weight well

Final Thoughts

Fever in a newborn can be stressful, but understanding what’s normal and what needs attention can make a big difference. Monitor your baby’s temperature, behavior, feeding, and diapers. Seek help quickly if your baby is very young, very unwell, or shows any warning signs. Staying calm, observant, and informed is one of the best ways you can care for your newborn during a fever.