You have probably heard your pediatrician say that a fever in your newborn baby is considered a medical emergency. Any baby who is less than 60 days old and spikes a fever (temperatures of 100.4°F/38°C or higher) should be brought into the emergency department for further evaluation. This is because the younger your baby is, the higher the chance of fever being a sign of a serious bacterial infection. Here’s what you need to know.

Checking your baby’s temperature

If your baby is very sleepy, isn’t waking up to feed, is irritable, inconsolable or warm to the touch, you should check their temperature.

Rectal temperatures are preferred but you can also use a forehead thermometer if you don’t have a rectal thermometer. Armpit or axillary temperatures are the least reliable.

Why is fever in a newborn considered a medical emergency?

Newborn babies are at higher risk for developing serious bacterial infections which can only be treated with antibiotics (often through an IV). These infections are very important to catch early, and fever is sometimes the only sign that your baby is sick.

What will happen when we get to the emergency department?

At the emergency department, your baby will be evaluated for bacterial infections as cause of fever. They may also be tested for common viruses, especially if other members of your household are sick.

The emergency department clinicians will collect blood and urine samples to look for infection (bacteremia if in the blood and a urinary tract infection if in the urine). If your baby is less than 21 days old, the doctors will also perform a lumbar puncture (also known as spinal tap) to look for signs of infection in the fluid that surrounds the brain and spinal cord (meningitis). If your baby is older than 21 days, they may use additional blood tests known as inflammatory markers and clinical appearance to determine whether a lumbar puncture is warranted.

Your baby may be started on antibiotics and may need to be admitted/observed in the hospital for at least 24-36 hours after the samples are collected. If antibiotics are started and no bacteria show up on the samples in this time frame, then the antibiotics will be discontinued. If the samples come back positive for bacteria, your baby may need to remain in the hospital on antibiotics and/or go home on antibiotics.

Thankfully, most fevers in babies are due to viral infections that improve with time. However, it is difficult to identify whether a young infant has a viral or serious bacterial infection just based on how they look. That is why it is important to reach out to a health care provider when your baby has a fever if they are under 60 days (or 2 months) old. It is also important to ensure that babies receive their vaccinations, as it will help prevent serious infections. Early recognition and treatment are the most important predictors of decreasing complications from serious infections.