What constitutes a fever in a newborn?

From the Guidelines

A fever in a newborn is a rectal temperature of 100.4°F (38°C) or higher and should always be considered a medical emergency requiring immediate attention. If your newborn has a fever, contact your doctor or go to the emergency room right away, as newborns can get very sick quickly 1. Do not give any fever-reducing medications like acetaminophen or ibuprofen to a newborn without medical supervision. When checking for fever in a newborn, use a rectal thermometer for the most accurate reading, as other methods like forehead or ear thermometers are less reliable in infants 1. Fever in newborns is concerning because their immune systems are still developing and cannot fight infections effectively. Common causes include serious bacterial infections like meningitis, urinary tract infections, or sepsis. Doctors will typically perform tests including blood work, urine tests, and possibly a spinal tap to determine the cause, and may start antibiotics while waiting for results 1. Always keep your newborn away from sick people and practice good hand hygiene to help prevent infections.

Some key points to consider when evaluating a newborn with fever include:

• The definition of fever: a rectal temperature of 100.4°F (38°C) or higher 1
• The importance of using a rectal thermometer for accurate temperature measurement 1
• The potential for serious bacterial infections, such as meningitis or sepsis 1
• The need for immediate medical attention if a newborn has a fever 1
• The importance of good hand hygiene and avoiding contact with sick people to prevent infections 1

It's also important to note that the evaluation and management of febrile newborns is evolving, and guidelines may vary depending on the specific clinical context and the availability of diagnostic tests and treatments 1. However, the key principle of prioritizing the health and safety of the newborn remains the same. If in doubt, it's always best to err on the side of caution and seek medical attention immediately.

From the Research

Definition of Fever in Newborns

• A fever in a newborn is defined as a rectal temperature over 100.4 degrees F 2
• Fever occurs when the hypothalamic thermoregulation center resets the temperature set point in response to a chain of events initiated by the inflammatory response 2

Evaluation and Management of Fever in Newborns

• All febrile infants younger than 28 days should receive a "full sepsis workup" and be admitted for parenteral antibiotic therapy 3
• Fever in newborns can be a sign of a serious bacterial infection, and evaluation should include observation, assessment of age and temperature risk factors, history and physical, and lab tests 2, 4
• The Yale Observation Scale can be used to aid in the assessment of how ill or "toxic" a child appears 2

Risk Factors and Causes of Fever in Newborns

• Risk factors for neonatal sepsis include central venous catheter use and prolonged hospitalization 5
• Common causes of fever in newborns include bacterial infections, such as group B Streptococcus and Escherichia coli 6
• Fever in newborns can also be caused by other factors, such as environmental factors, and can occur in the first few days of life 6

Treatment of Fever in Newborns

• Acetaminophen remains the antipyretic of choice for treating fever in newborns 2
• Antibiotic therapy should be started immediately in newborns with suspected sepsis or serious bacterial infection 5, 3
• Tepid sponge baths may be useful for children with a history of febrile seizures or liver disease, but are only slightly more effective than acetaminophen alone in reducing fevers 2