An infection is due to harmful germs (bacteria, fungi, or viruses) in the baby's body. Infections can begin before, during, or after birth. All babies have immune systems that are still developing. This system's job is to fight germs. A newborn's immune system may not be ready to fight an infection. Premature babies are at an even higher risk of infection than full-term babies. This is because babies get antibodies (infection-fighting substances) from the birth parent when they are in the uterus. Preemies don't receive several weeks of antibodies since they are born early.