Acute birth asphyxia can be defined as an interference with respiration resulting in hypoxia and tissue acidosis occurring around the time of birth. Because tissue acidosis is commonly associated with circulating acidemia, many clinicians assume that infants born with acute birth asphyxia invariably demonstrate acidemia in umbilical artery blood at birth. Furthermore, they assume that asphyxiated infants will not suffer brain injury unless they demonstrate severe acidemia.