Infant Overheating and Hyperthermia

Thermal stress has been indentified as a risk factor for Sudden Infant Death Syndrome (SIDS) in a number of studies. Infants who died of SIDS often had a preceding upper respiratory tract infection and may have had a fever.

Furthermore, otherwise healthy babies may become overheated when they are covered or wrapped excessively. Heavy wrapping and excessive room heating independently increased the risk of SIDS, especially in infants older than 70 days.

Hyperthermia may require an interaction among multiple risk factors, for example an increase of SIDS was found among infants who slept in the prone position in addition to wrapping, recent illness or room heating. Infants lose much of their heat through the head and face, particularly when the rest of the body is covered. Therefore, prone sleeping may increase the risk of rebreathing, but also dramatically reduce the capacity for heat loss. The elevated risk of SIDS when prone sleeping and swaddling, recent illness or elevated room temperature were also present suggest an interaction between prone sleeping and the risk of overheating in the pathogenesis of SIDS.

Another hypothesis that may link hyperthermia with SIDS is that a combination of a sudden decrease in inhaled oxygen and elevated body temperature might prevent an infant from coping with apnea. Apnea is defined as "an unexplained episode of cessation of breathing for 20 seconds or longer, or a shorter respiratory pause associated with bradycardia (low heart rate, cyanosis [blue skin color due to decreased oxygen in the blood], pallor [pale skin appearance] , and/or marked hypotonia [decrease in the muscle tone])."

In conclusion, it seems probable that some deaths diagnosed as SIDS are in part, at least, from elevated body temperature resulting from increased environmental temperatures, febrile illness, over bundling and prone sleeping position, or a combination of these factors.