Numerous studies of the blood of new-born infants have established the fact that the red corpuscles and hemoglobin are much higher during this period than in adult life. The figures given by different observers vary, however, quite widely. This variation is especially striking in the hemoglobin determinations.
Lippman1 has recently completely summarized the literature on the blood during the new-born period. He adds the results of his own study of the blood of seventy-one infants during the first 48 hours of life. This observer found the average red cell count at birth to be 5.2 million per cubic millimeter. At the end of six hours the average count had risen to 5.65 million, the increase being due seemingly to greater activity of the hemopoietic organs. At eighteen hours the count had fallen to 5.4 million, at which point it remained for the rest of the fortyeight hour period.
HADEN RL, NEFF FC. THE VOLUME INDEX AND COLOR INDEX OF THE RED BLOOD CORPUSCLES IN NEWBORN INFANTS. Am J Dis Child. 1924;28(4):458-463. doi:10.1001/archpedi.1924.04120220054009