POSTNATAL CHANGES IN SOME RED CELL PARAMETERS

Abstract

Summary The red blood picture was studied in detail from birth to 12 weeks. The low point in the red cell count was reached in the seventh week, which represented the turning point from a negative to a positive balance between cell production and destruction. From the dynamics of the total number of circulating red cells it was concluded that, although erythropoiesis slows down after birth, a considerable amount of red cell production takes place during the first few postnatal weeks. The MCHC increased significantly over the first 5–6 postnatal weeks and remained constant thereafter. Macrocytes predominated at birth. Their percentage distribution decreased after the second week with a corresponding increase in microcytes. The red cell density distribution curve in the neonatal period is sigmoid in shape. The range of densities is, however, wider than in the adult. The curve shifts gradually to the heavy side from birth to 5 weeks, while from 5 to 12 weeks a shift back to the light side is observed. Macrocytes preponderate in the light fractions.