Many reasons. Some babies who have infections right after birth need to stay in the nicu for treatment and close monitoring. Some babies may have underdeveloped lungs (such as premature infants) and may require a ventilator to breathe. Some premature babies may be in the nicu to work on feeding, which may require a special feeding tube. Others may have heart problems that need medical or surgical treatment.
Higher level of Care. When babies are born prematurely(generally less than 35 weeks) , have respiratory problems, or a congenital problem with the heart or other system, or infection, they may require a level of care that is not available/ appropriate for a general level i nursery. Nicus have experts called neonatologists who manage and supervise care of babies with special needs. Nurses have advanced training as well.