Premature baby. View of a premature baby in an incubator being bottle-fed with human milk. This contains the perfect balance of nutrients for human babies, as well as antibodies to protect against infection. The incubator provides the baby with the ideal environment for survival. Premature babies must first be fed using a nasogastric tube as they have no sucking reflex and only poor swallowing ability. Only later can they be fed as seen here. Premature babies are usually kept in hospital until they weigh about 2.25 kg and are feeding well. The baby's eyes are covered to stop them from being damaged by ultraviolet light used during phototherapy to treat neonatal jaundice.