The vast majority of newborns enter the world healthy. But sometimes, infants develop conditions that require medical tests and treatment. Newborns are particularly susceptible to certain diseases, much more so than older children and adults. Their new immune systems aren't adequately developed to fight the bacteria, viruses, and parasites that cause these infections. As a result, when newborns get sick, they may need to spend time in the hospital — or even the neonatal intensive care unit (NICU) — to recover. Although it can be frightening to see your baby hospitalized, a hospital stay is often the best way back to good health for a sick newborn. Many infections cause similar symptoms. Call your child's doctor or seek emergency medical care if your new baby shows any of these possible signs of infection: poor feeding, breathing difficulty, listlessness, decreased or elevated temperatureunusual skin rash or change in skin color, persistent crying, unusual irritability, A marked change in a baby's behavior, such as suddenly sleeping all the time or not sleeping much at all, can also be an indication that something isn't right. These signs are of even greater concern if the baby is less than 2 months old. To make ensure good health, have your baby checked by a doctor right away if you suspect a problem. Group B streptococcus is a common type of bacterium that can cause a variety of infections in newborns. Some of the most common are sepsis, pneumonia, and meningitis. Babies usually get the bacteria from their mothers during birth — many pregnant women carry these bacteria in the rectum