Worry comes with the territory of being a new mom. While not all fret-worthy things warrant a call to your lil one's pediatrician, an infant's fever is nothing to chance — especially during flu season. According to the Mayo Clinic:

Mild fevers are common and usually harmless, but it's important to keep an eye on the thermometer. Contact the doctor if your baby is younger than age 2 months and has a rectal temperature of 100.4 F or higher or if your older infant has an oral or ear temperature of 102 F or higher.

So be sure to keep an eye on your bundle of joy's temperature. You can usually tell by touch if she is hotter than normal, but a rectal temperature will give the most accurate reading. As always, if you're unsure, best practice is to call the doctor.