The premature infant's body is unable to maintain body heat. To prevent hypothermia, a potentially dangerous loss of body heat, the infant is kept warm on a heated bed, either inside a draft-free enclosure (isolette or incubator) or under a radiant heater.

As the infant's nervous system, skin, and metabolism mature, the infant becomes less vulnerable to hypothermia. At about 34 weeks' gestation, a premature infant usually can be moved into an open crib.