Elevation of body temperature to greater than 38°C was observed in several noncooled infants in the NICHD and CoolCap trials and was associated with a worse outcome in the CoolCap trial.11,24 A rectal temperature of more than 38°C was also noted in some noncooled infants in TOBY. Experi- mental data showing that pyrexia may adversely affect neurodevelopment support the possibility that increased temperatures may contribute to the poorer outcomes seen in the noncooled groups; however, it is also possible that the relationship between higher elevation of body temperature and poor outcome reflects reverse causation (i.e., as- phyxia resulting in impairment of temperature regulation).