The 6”y:”y Composition of Fetal Hemoglobin in Fetuses and Newborns

heterogeneity was evaluated by was identical to the ratio found in the electrophoresis on polyacrylamide gels. globin protein accumulated by 20 wk. The The mean G was 70% in 1 9 newborns, proportion of was also identical in 6 similar to the published value of 73% paired samples, at 20-wk gestation and at obtained by amino acid analysis of the y birth. Thus, G y production does not decline CG-3 peptide. In 29 fetuses at 18-20-wk with respect to A in utero at the time of gestation. G,,, , was 71 %. The values were onset of the HbF:HbA switch.