In contrast, studies of neonatal cooling have approached this topic from the point of Definitional problems of encephalopathy aside, evidence from 11 randomized clinical trials indicates that therapeutic cooling decreases mortality and long-term neurologicalmorbidity rates by 15% (95% confidence interval [CI]10–20%) and reduces the risk of CP by 12% (95% CI6–18%), with a corresponding number needed to treat of 8 (95% CI 6–17).6 It is unclear why so many eligible neonates fail to benefit from therapeutic cooling.We examine the possibility that the underlying aetiology of neonatal encephalopathy in infants selected for cooling influences their response to treatment, and that differences in study objectives, design, and definitions contribute to the differing reports of the attribution of aetiology throughout the literature.