This is a multicentre prospective randomised controlled trial to determine whether a reduction of body temperature by 3-4°C following perinatal asphyxia improves survival without neurodevelopmental disability. Full term infants will be randomised within 6 hours of birth to either a control group with the rectal temperature kept at 37 ± 0.2°C or to whole body cooling with the rectal temperature kept at 33.5 ± 0.5°C for 72 hours followed by slow rewarming. The outcome will be assessed at 18 months of age by survival and neurological and neurodevelopmental testing. Eligibility criteria: Term infants less than 6 hours after birth with moderate or severe perinatal asphyxia (a combination of clinical and EEG criteria). Exclusion criteria: Infants expected to be 6 hours of age at the time of randomisation or infants with major congenital abnormalities. Intervention: Intensive care with whole body cooling versus intensive care without whole body cooling (babies are cooled to 33.5°C for 72 hours) Main Outcomes: Death and severe neurodevelopmental impairment at 18 months of age Secondary Outcomes: Cerebral thrombosis or haemorrhage, persistent hypotension, pulmonary hypertension, abnormal coagulation, arrhythmia and sepsis in the neonatal period. Neurological impairments at 18 months Number of patients required: 236. On 30th November 2006, when recruitment closed, 325 babies had been recruited.

Hypothesis: Prolonged whole body cooling in term infants with perinatal asphyxial encephalopathy reduces death and severe neurodevelopmental disability. This study aims to determine whether whole body cooling to 33-34°C is a safe treatment that improves survival, without severe neurological or neurodevelopmental impairments at 18 months, of term infants suffering perinatal asphyxial encephalopathy.