Top 4 NICU Discharge Questions About Temperature

NICU Growing Home Series


How Do I Know If My Baby Is Too Warm or Too Cold?

The best way to tell is to take your baby’s temperature. Continue to take your baby’s temperature with every feeding as your baby acclimates to the new home environment outside of the NICU. Your home should be a comfortable low to mid-70 degrees, keeping in mind the season and how your baby is dressed.

Dressing for the activity and season: The best way to tell if your baby is warm enough is to look at and touch your baby’s skin.

  • If your baby’s skin looks blotchy and cool or if your baby’s hands and feet feel cold, you may want to add additional clothing such as socks or a hat. If you are with your baby in the daytime you can cover your baby with a blanket.
  • If your baby’s skin looks red or flushed or if your baby appears sweaty, remove a blanket or a piece of clothing.
  • It’s important to practice safe sleep when your baby is napping away from you or in its crib at night. Keeping your baby warm and comfortable by dressing your baby in a sleeper or a blanket sleeper. Additional loose blankets, bumper pads, and stuffed animals are NOT recommended in cribs as they increase the risk of SIDS. Keeping your baby safe while sleeping should be your number one priority.

How Do I Take My Baby’s Temperature?

The NICU staff should have shown you how to take your baby’s temperature before discharge from the hospital. Most NICUs will give you a digital thermometer to take home with you. If not, you can purchase one at any department store or local pharmacy.

The best and most accurate way to take your baby’s temperature is either under the arm (axillary) or in the bottom(Rectal). Oral temperatures should not be performed on babies. Temporal (forehead) temperature taking is a growing trend, but the accuracy of this method at home is not reliable.

Taking an Axillary (underarm) Temperature:

NORMAL TEMPERATURE is between 97.6 and 99.0 under the arm.

  • Turn the thermometer on by pressing the button. Look for the “L” and the small “f” for Fahrenheit.
  • Place the silver tip of the thermometer under your baby’s armpit making sure that it is in contact with the skin on the arm and the skin in the cove under the arm.
  • Hold your baby’s arm down next to the side of the chest, keeping the thermometer in place.
  • Keep the thermometer in place until you hear a beep and/or you see the small “f” stop flashing. This step usually takes about a minute, but sometimes feels a lot longer. Be patient, it is very important to wait until the final reading.

**If your baby’s temperature is out of range under the arm, always double check it with a rectal temperature. **

Taking a Rectal (in the bottom) Temperature:

NORMAL TEMPERATURE is between 98.0 and 100.4 rectally.

  • Use a digital thermometer label rectal thermometer. Always have a separate thermometer for taking a rectal temperature.
  • Make sure you use pre-lubricated covers, lubrication gel, or Vaseline on the silver thermometer tip.
  • Hold your baby on their abdomen across your lap or cradle your baby on their side, keeping your baby in a safe and secure position.
  • Remove the diaper and place the silver tip of the thermometer into your baby’s rectum, insert no more than a half (1/2) an inch.
  • Hold the thermometer in place until you hear a beep and/or you see the small “f” stop flashing. This step usually takes a minute, but can sometimes feel a lot longer. It is important to wait for the final reading to get an accurate temperature.

How Do I Know If My Baby Is Sick?

As a parent, you know your baby better than anyone. A change in your baby’s behavior could be a sign that your baby is sick. These include:

  • A change in your baby’s breathing pattern. Some premature babies are more susceptible to respiratory infections and colds. It’s important to keep a close eye on how your baby is breathing. Is it labored (fast) or does it appear your baby is struggling? Is your baby coughing or wheezing? (A raspy sound with breathing)
  • Excessive crying, unusual fussing, or irritability.
  • Blue, pale, or mottled skin color.
  • Change in eating pattern. Is your baby not eating as much as before? Do you have to wake your baby for feedings? Is your baby struggling to get in the volume needed?
  • A change in your baby’s temperature. Either a fever or a decrease in temperature that is not corrected with environmental changes. Having a fever or if your baby is too cold could be an indication of an infection.

Premature babies are more susceptible to dehydration and can become sick very quickly from loss of fluid or nutrients. Some additional signs include:

  • Vomiting most of all of their feeding.
  • Frequent liquid stools
  • A decrease in the number of wet diapers, dry diapers between feeds, or urine that is dark in color.

When Should I Call My Baby’s Doctor?

If you feel your baby is sick, do not hesitate to call your pediatrician or if needed, bring your infant to the emergency room. 

When calling your baby’s doctor it is always good practice to have already taken their temperature. Do not just feel your baby’s forehead. It’s important to have accurate information so that the triage nurse can get your baby in to see the pediatrician as soon as possible if needed. If your baby’s axillary temperature is elevated or is low, they will more than likely want you to have a rectal temperature as well. 

Your baby should be seen by a doctor if:

  • Your premature baby is under two months of age and has an axillary temperature greater than 99 degrees Fahrenheit or a temperature of 100.4 degrees Fahrenheit rectally.
  • Your premature baby has an axillary temperature greater than 99 degrees Fahrenheit or 100.4 degrees Fahrenheit rectally and is showing other signs of illness.
  • Your baby has a fever that has been present for more than two (2) days.
  • Your baby’s temperature is less than 97 degrees Fahrenheit. A low temperature or the inability to maintain a normal temperature range can be a sing of illness or infection.
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Article Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Academy of Pediatrics. Reduce the risk of SIDS & suffocation. Updated January 2017.

  2. Charafeddine L, Tamim H, Hassouna H, Akel R, Nabulsi M. Axillary and rectal thermometry in the newborn: do they agree?. BMC Res Notes. 2014;(7):584.  doi:10.1186/1756-0500-7-584

  3. Nationwide Children’s Hospital. Temperature: digital and glass thermometers. Updated February 2017.

  4. American Academy of Family Physicians. Recognizing newborn illnesses. Updated February 2018.

  5. UnityPoint Health Meriter. Illness and taking temperature.

Additional Reading
  • Illness and Taking Temperature : Meriter Health Services. (n.d.). Retrieved from
  • Premature Babies Should Have Temperature Monitored at 2 Sites. (n.d.). Retrieved from
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  • Thermal Stability of the Premature Infant in NICU. (n.d.). Retrieved from