A premature baby is who is born very early, before 37 weeks of pregnancy. Premature babies may not be fully developed at birth. They may have more health problems and may need to stay in the hospital longer than babies born later. They need extensive care and constant monitoring.
Premature babies stay in the NICU until their organs develop enough to stay alive without medical support. Some babies need NICU care for weeks or months until they can breathe on their own, eat by mouth and maintain their body temperature and body weight.