the change in the blood oxygen affinity which occurs in the foetus and the newborn have been attributed in some species to the presence of a foetal haemoglobin ( hbf ) which differs from the adult haemoglobin ( hba ) either by an intrinsically higher oxygen affinity , independant of any intracellular cofactor , or by an impaired reactivity towards cofactors which alter haemoglobin oxygen affinity by directly interacting with the haemoglobin molecule ( 2,3 dpg , co2 ) .
C0019016
hba
C0019046
haemoglobin