Because their immune systems aren’t mature, infants are more prone to serious infections, especially during the first three months, which is why it’s important to see your doc if your newborn has a fever. But please don’t assume that a baby has to have a fever for something serious to be going on; sometimes their smoke alarms have been unplugged. If your child doesn’t look right or you just have a feeling something is up, it’s never—repeat, never—wrong to call your doc. We welcome those kinds of false alarms. Mothers’ instincts have saved many young lives.
Answer excerpted from You Raising Your Child