Postnatal fetal and adult hemoglobin synthesis in early preterm newborn infants.

Studies were carried out during the postnatal period in infants born at or before the 32nd wk of gestation to determine the proportion of fetal hemoglobin (Hb F) and adult hemoglobin (Hb A) being synthesized, and to compare these studies to those previously reported on at birth from normal newborn infants 25-43 wk gestation. When the pretern infants reached the postconceptional age corresponding to term, their Hb A and Hb F synthesis was compared to a group of newborn infants at term. 53 blood samples from 25 preterm and 11 full-term infants were incubated in an amino acid mixture containing [(14)C]leucine, and column-chromatographed on DEAE-Sephadex for separation of Hb F and Hb A fractions. The completeness of the DEAE-Sephadex separation of Hb F and Hb A was confirmed by globin chain chromatography with the use of carboxymethylcellulose. The rate of transition from Hb F to Hb A synthesis postnatally in the preterm infants resembled that reflecting the in utero transition. At the postconceptional age corresponding to term, there was no difference in the relative amounts of Hb F and Hb A being synthesized by the preterm infants and by the term infants. The birth process did not alter the rate of transition from Hb F to Hb A.