The association of cerebral palsy with birth asphyxia: a definitional quagmire

Aim The aim of this study was to investigate whether current literature provides a useful body of evidence reflecting the proportion of cerebral palsy (CP) that is attributable to birth asphyxia. Method We identified 23 studies conducted between 1986 and 2010 that provided data on intrapartum risks of CP. Results The proportion of CP with birth asphyxia as a precursor (case exposure rate) varied from less than 3% to over 50% in the 23 studies reviewed. The studies were heterogeneous in many regards, including the definitions for birth asphyxia and the outcome of CP. Interpretations Current data do not support the belief, widely held in the medical and legal communities, that birth asphyxia can be recognized reliably and specifically, or that much of CP is due to birth asphyxia. The very high case exposure rates linking birth asphyxia to CP can probably be attributed to several factors: the fact that the clinical picture at birth cannot specifically identify birth asphyxia; the definition of CP employed; and confusion of proximal effects – results – with causes. Further research is needed.