Haemoglobin and red cells in the human foetus; III. Foetal and adult haemoglobin.

In 1866 Korber found chemical differences between haemoglobin obtained from human placental blood and that from normal adult blood. Since then it has been clearly demonstrated that there are many important differences between human and animal and between foetal and adult haemoglobins (Kroger, 1888; Bischoff and Schulte, 1926; Haurowitz, 1930, 1935; Trought, 1932; Brinkman, Wildschut and Wittermans, 1934; Hill, 1935; Brinkman and Jonxis, 1935; Jope and O'Brien, 1949). Haselhorst and Stromberger (1930, 1932) showed that the blood of the human foetus possessed a higher affinity for oxygen than that of its mother, but Hill (1935) found that human foetal haemoglobin had a lower affinity than human adult haemoglobin. This apparent anomaly was explained by the work of McCarthy (1943), who showed that the affinity of the haemoglobins for oxygen was greatly modified when they were within a corpuscle. Adult corpuscles caused a marked decrease in the oxygen affinity of their contained haemoglobin, while foetal corpuscles had little effect on the affinity of foetal haemoglobin for oxygen. Recently, Allen, Wyman and Smith (1953) have re-studied the oxygen affinity of human haemoglobins. Unlike Hill (1935) and Haurowitz (1935) they found no difference between the affinity for oxygen of the haemoglobin of the human foetus and that of its mother, provided that the haemoglobin solutions were so treated that the concentrations of dialysable substances were identical. They also found that the haemoglobin from one foetus at 31 weeks had the same affinity as the haemoglobins of term foetuses and of their mothers. Most investigators have been concerned with a study of the physical, chemical and other characteristics of human haemoglobins, and little information is available of the relative proportions ofeach type of haemoglobin in the blood of the human foetus at various stages of gestation, although such information is available for the sheep foetus. Karvonen (1949) found that adult haemoglobin first appeared in the sheep foetus at or about the 105th day and that at term 50% of the haemoglobin was adult in type. Beaven, Hoch and Holiday (1951), in one human foetus, at 20 weeks' gestation, found that 6% of the haemoglobin was of the adult type and Schulman (1953) that there was at least 10% adult haemoglobin in the blood of premature infants. Many investigators have, however, studied the proportion of adult haemoglobin in the cord blood of the foetus at birth, at or near full term, and their results are shown in Table 1, from which it can be seen that