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Lisa Black

A febrile infant is a baby whose temperature reaches or exceeds 100.4 degrees Farenheit

When an infant younger than two months old develops a fever, it is natural for families and their pediatricians to be concerned. While most fevers do not lead to severe illness, it can be challenging to immediately identify the cause of a baby’s fever while avoiding unnecessary tests or hospitalizations.

The American Academy of Pediatrics addresses the many questions raised in evaluating otherwise well-appearing infants between 8-60 days old who develop a fever at or above 100.4 degrees Fahrenheit (38 degrees Celsius) in a new clinical practice guideline. The guideline, “Evaluation and Management of Well-Appearing Febrile Infants 8–60 Days Old,” is published in the August 2021 Pediatrics (published online July 19).

“Babies at this age are too young to describe how they feel, and so a fever is an important signal that something is wrong,” said Benard Dreyer, MD, FAAP, an author of the guideline, written by the AAP Council on Quality Improvement and Patient Safety’s Subcommittee on Febrile Infants.

“As we learn more about the risks and benefits of treating infants, we offer evidence-based recommendations for physicians to consider. We also acknowledge the significant role that parents play in the decision-making process as informed participants in the process.”

About 14 out of every 1,000 healthy infants born full term develop a fever during the ages 8 days to 60 days old, according to the AAP. More than 10% of febrile infants are diagnosed with a urinary tract infection. The likelihood of a more invasive bacterial infection is much lower, with fewer than .05% of infants developing meningitis, the most serious infection. Some other infections in young infants include pneumonia, sepsis and gastroenteritis.

The AAP guideline breaks down recommendations for three infant age ranges: 8 to 21 days; 22 to 28 days; and 29 to 60 days. Newborns in their first week of life have different needs and are not included in the report.

The guideline, which underwent an evidence review commissioned by the Agency for Healthcare Research and Quality, breaks down recommendations for evaluation and care, and ranks the quality of available evidence on which the recommendations are based. Risks and benefits also are detailed, including those concerning invasive procedures such as a lumbar puncture or bladder catheterization.

“Whenever a baby this young develops a fever, parents should call their pediatrician to have their baby evaluated,” said Sean O’Leary, MD, MPH, FAAP, an author of the guideline. “Most children do well, but some have serious infections, and at such a young age, it’s next to impossible for a parent to distinguish who has a serious infection and who doesn’t.”

More information for parents is available in this article:

Fever and Your Baby -

To request an interview, contact AAP Public Affairs.


The American Academy of Pediatrics is an organization of 67,000 primary care pediatricians, pediatric medical subspecialists and pediatric surgical specialists dedicated to the health, safety and well-being of infants, children, adolescents and young adults.

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