Like the temperature of an adult, a baby’s temperature can fluctuate slightly based on things like time of day, activity, and even how their temperature was taken.
A child’s temperature may be as low as 95.8°F (35.5°C) in the morning and as high as 99.9°F (37.7°C) late in the day when measured with an oral thermometer. These temperatures would still be considered in the typical range, according to the American Academy of Pediatrics (AAP).
But taking an oral temperature in a baby isn’t accurate, since they can’t hold the thermometer under their tongue. When taken with a rectal thermometer, a baby’s temperature may be anywhere from 96.8°F (36°C) in the morning to 100.3°F (37.9°C) late in the day, according to the AAP.
Taking a baby’s temperature under their arm (axillary) is another commonly used method. It’s easier to do but still less accurate than taking a rectal temperature. The axillary temperature is usually at least a degree lower than the rectal temperature.
If your baby’s rectal temperature drops below 95°F (35°C), they’re considered to have hypothermia, per the AAP.
Hypothermia is low body temperature. A low body temperature in babies can be dangerous and, though rare, may lead to death.
Read on to learn more about low body temperature in babies, including causes and next steps.
In addition to a low body temperature, other symptoms of hypothermia in babies include:
- poor feeding
- weak cry
- pale, cool skin
- trouble breathing
Premature birth and low birth weight
Infants born at less than 28 weeks’ gestation have the highest risk of developing hypothermia, according to
Low birth weight is another risk factor. Babies who are 3.3 pounds (1.5 kilograms) or fewer are 31 to 78 percent more likely to develop hypothermia immediately after birth than babies with a higher birth weight, based on this 2013 research.
Early babies and those with low birth weight run a higher risk of hypothermia because of their large surface-area-to-volume ratio. This refers to the fact that a baby is a tiny human — especially if they’re born early or with low birth weight — which means they can’t hold as much heat inside their bodies as older children or adults.
Additional contributing factors are their:
- lack of insulating body fat
- still developing nervous system
- inability to efficiently conduct heat
Shortly after a hospital birth, if your baby is premature or has a low birth weight, they’ll be placed in specially designed bassinets that have warming lights and heated mattresses.
When you bring your baby home, use these tips to help regulate their body temperature:
- Swaddle or wrap your baby snugly in a single blanket.
- Place a hat on your baby if they’ll be out in a cold environment to help reduce heat loss.
- Limit baths. Water evaporating on skin can lower body temperature, so bathing (other than sponge bathing) isn’t recommended for babies until after their umbilical cord falls off around 2 weeks of age.
Cold birth environment
Many babies, even full-term ones, are born with a near hypothermic body temperature. Being born in a cold space can quickly cause your baby’s body temperature to drop.
In the hospital, a number of protocols may be in place to warm up your baby, including:
- immediately drying the baby after delivery to remove wet and cold amniotic fluid
- placing the baby in a bassinet with radiant heat
- using heated mattresses and blanket wraps
- encouraging skin-on-skin contact with a parent
- delaying the first bath until at least 12 hours after birth, when a baby may be a little more efficient at staying warm
If your baby is born outside of a hospital, it’s important to keep them warm using similar methods. While you may not have access to a heated mattress, you can dry baby off, use skin-to-skin contact, and swaddle or wrap them in a blanket.
Hypoglycemia is a condition in which there’s too little glucose, or blood sugar, circulating in your body. Glucose is used by your body for energy.
A baby can become hypoglycemic at birth or soon after because of:
- birth abnormalities
- the birthing parent’s health during pregnancy
To help prevent hypoglycemia in your baby:
- Maintain a healthy diet during pregnancy and follow your doctor’s recommendations for weight gain.
- Manage diabetes during pregnancy if you have that condition, and get tested for gestational diabetes.
- Keep your baby on a regular feeding schedule.
Some serious infections have been associated with a drop in body temperature.
Meningitis is an inflammation of the membranes that surround the spinal cord. It can sometimes cause a fever in babies, but in other cases it may cause a lower-than-average body temperature.
Sepsis, a dangerous bacterial infection of the blood, commonly causes a low body temperature in infants. In some cases, it may lead to a fever instead.
Both meningitis and sepsis are serious life threatening infections. Get immediate medical help if you notice several of these symptoms in your baby:
- pale, clammy, blotchy skin, and sometimes a rash
- poor feeding
- fast breathing
- moaning cry
- cold hands and feet
Low body temperature can be serious.
When a baby’s temperature drops below the typical range, their body uses more oxygen in an effort to create more body warmth. That increase can put a huge stress on a tiny body.
In some cases, low body temperature may even lead to death, though this is exceedingly rare in the United States.
If you suspect your baby has a low body temperature, the first thing you should do is take their temperature!
Rectal temperatures may be more accurate, but if you don’t have a rectal thermometer, you can use an axillary thermometer. Never use an axillary thermometer in the rectum or vice versa.
If your baby’s temperature is low, try to increase it by:
- adding clothing
- using your body heat
- swaddling them in a blanket
If these steps don’t work and their temperature remains low, call their pediatrician right away.
The doctor may direct you to seek emergency medical help. If you can’t reach the doctor and your baby seems ill, go to the nearest emergency room.
Early treatment can help reduce the risk for serious complications. Always call your baby’s doctor if you suspect something is wrong. It’s better to err on the side of caution.
A rectal temperature lower than 95°F (35°C) puts a baby at increased risk for:
- respiratory problems
- blood clotting disorders
Babies lose heat more quickly than adults. If you notice any of the symptoms of hypothermia in babies — such as rapid or difficult breathing, pale skin, lethargy or a lack of interest in eating — try to increase your baby’s temperature with extra clothing and warm liquids, and seek medical help right away.
Be especially attentive if your baby was born early or at a low birth weight, as these children are more likely to experience a low body temperature than full-term babies.