Thermoregulation, or the ability to maintain a stable core body temperature, is a key component of caring for newborns. The World Health Organization (WHO) recommends that newborns maintain a temperature of 36.5 – 37.5 °C (97.7 – 99.5 °F) after birth (Dunne et al., 2024). Newborn temperatures can range widely within the first 48 hours of life (Zeichner, 2025).
What is hypothermia?
Newborn hypothermia is defined as a temperature below 36.5 °C (<97.7 °F). Low birth weight and preterm infants tend to have a higher risk for developing hypothermia (Dang et al., 2023). Many infants are below the WHO threshold for hypothermia (Zeichner, 2025), so it is important to learn how to take their temperatures and look out for concerning signs and symptoms.
How to Take Your Baby’s Temperature
Using a rectal thermometer is the gold standard for taking a newborn’s temperature.
- Apply petroleum jelly to the tip of the rectal thermometer.
- Rest your baby on their stomach, either on your lap or on a changing table.
- Insert the rectal thermometer one inch into your baby’s rectum.
- Hold the thermometer in place for two minutes. Do not let go of the thermometer and keep your baby as still as possible.
- Remove the thermometer and read the temperature.
If taking a rectal temperature is not possible, an axillary (armpit) temperature can be taken (Torpy et al., 2004).
What can I do about my baby’s low temperature?
Globally, complications from preterm birth are the leading cause of death among kids under the age of five. Even in high-income countries like the U.S., hypothermia in newborns is common and remains a concern (Dunne et al., 2024; Frade Garcia et al., 2023).
In response, the World Health Organization launched a global clinical practice guide called Kangaroo Mother Care (KMC). KMC combines breast milk feeding with prolonged skin-to-skin contact and has several positive effects on both parent and baby (WHO, 2025). Infants who received skin-to-skin contact 24 hours after birth had a lower incidence of hypothermia (Nimbalkar et al., 2014).
Contact your pediatric healthcare provider for newborn temperatures outside of the WHO’s recommended 36.5 – 37.5 °C (97.7 – 99.5 °F).
When is hypothermia a problem for older kids?
While our patients in Long Beach are not often at risk of environmental hypothermia, preparing for cold weather can still feel unfamiliar.
Cold Weather Wear
- Choose warm options, like down coats
- Dress kids in multiple thin layers and give them one more layer than an adult would normally wear.
- Wear accessories like warm boots, gloves/mittens, and hats.
- For cold sleeping environments, avoid large, loose bedding. Extra quilts, pillows, sheepskins, and the like can be a suffocation risk. Pick something without bulk, like warm-rated sleepers or wearable blankets.
In your older kids, watch out for:
- Shivering
- Lethargy
- Clumsiness
- Slurred speech
What about hyperthermia?
Hyperthermia, or heat stress, can occur in some infants who have difficulty thermoregulating. Infants who overheat can have complications with normal body functions, and may overheat due to thermal stress (e.g., outdoor temperatures, excessive insulation from clothing or bedding, sharing a bed, wearing a head covering). Hyperthermia is a common finding in sudden infant death syndrome (SIDS) (Bach & Libert, 2022).
Fevers in infants, particularly those under 3 months, can also indicate a severe infection. Because of their immature immune systems, infants under 3 months of age with a fever can be a possible emergency. Please do not give your infant a fever reducer until your provider can see them.
Contact your pediatric healthcare provider for newborn temperatures outside of the WHO’s recommended 36.5 – 37.5 °C (97.7 – 99.5 °F).
References
American Academy of Pediatrics [AAP]. (2023, January 25). Cold Weather Safety for Children: Preventing Frostbite & Hypothermia. HealthyChildren.Org. https://www.healthychildren.org/English/safety-prevention/at-play/Pages/Cold-Weather-Safety.aspx
Bach, V., & Libert, J.-P. (2022). Hyperthermia and Heat Stress as Risk Factors for Sudden Infant Death Syndrome: A Narrative Review. Frontiers in Pediatrics, 10, 816136. https://doi.org/10.3389/fped.2022.816136
Dang, R., Patel, A. I., Weng, Y., Schroeder, A. R., Lee, H. C., Aby, J., & Frymoyer, A. (2023). Incidence of Neonatal Hypothermia in the Newborn Nursery and Associated Factors. JAMA Network Open, 6(8), e2331011. https://doi.org/10.1001/jamanetworkopen.2023.31011
Dunne, E. A., O’Donnell, C. P. F., Nakstad, B., & McCarthy, L. K. (2024). Thermoregulation for very preterm infants in the delivery room: A narrative review. Pediatric Research, 95(6), 1448–1454. https://doi.org/10.1038/s41390-023-02902-w
Frade Garcia, A., Edwards, E. M., de Andrade Lopes, J. M., Tooke, L., Assenga, E., Ehret, D. E. Y., & Hansen, A. (2023). Neonatal Admission Temperature in Middle- and High-Income Countries. Pediatrics, 152(3), e2023061607. https://doi.org/10.1542/peds.2023-061607
Nimbalkar, S. M., Patel, V. K., Patel, D. V., Nimbalkar, A. S., Sethi, A., & Phatak, A. (2014). Effect of early skin-to-skin contact following normal delivery on incidence of hypothermia in neonates more than 1800 g: Randomized control trial. Journal of Perinatology: Official Journal of the California Perinatal Association, 34(5), 364–368. https://doi.org/10.1038/jp.2014.15
Torpy, J. M., Lynm, C., & Glass, R. M. (2004). Fever in Infants. JAMA, 291(10), 1284. https://doi.org/10.1001/jama.291.10.1284
World Health Organization [WHO]. (2025, November 14). WHO promotes lifesaving intervention for small and preterm babies on first official World Prematurity Day. Word Health Organization. https://www.who.int/news/item/14-11-2025-who-promotes-lifesaving-intervention-for-small-and-preterm-babies-on-first-official-world-prematurity-day
Yan, J., Ren, J.-D., Zhang, J., Li, J., Zhang, X., Ma, Y., & Gao, L. (2023). The Short and Long Term Consequences of Delayed Cord Clamping on Late Pre-Term Infants. International Journal of Women’s Health, 15, 361–368. https://doi.org/10.2147/IJWH.S385800
Zeichner, E. (2025). A Better Understanding of Normal Newborn Temperature Percentiles. AAP Blog. https://publications.aap.org/journal-blogs/blog/32810/A-Better-Understanding-of-Normal-Newborn
