Hino K

EVALUATION OF EXTRA-UTERINE ADAPTATION OF PREMATURE NEONATES AND IUGR INFANTS BASED ON HbF SWITCHING

The switching of HbF to HbA was observed in 40-week AFD infants. Four weeks post partum HbF was 65%, decreasing to 50% at eight weeks. Premature neonates, however, took 3 weeks longer to reach a similar level. This phenomenon in premature neonates is thought to be related to their immaturity. To determine whether the HbF switching ratio of IUGR infants is also lower m than that of normal infants, C-leucine was adminstered to HbF in red blood cells in umbilical blood to judge by the synthesis ratio. The synthesis ratio in 28-week premature neonates was 91%, significantly higher than the 65% ratio of term infants. In IUGR infants as well, the ratio of 73% indicated an obvious delay in HbF switching compared with term AFD infants. Moreover, the concentration of 2,3DPG in IUGR infants was often low at birth, also indicating a delay in extra-uterine adaptation. With IUGR neonates it was found that HbF switching to HbA was delayed and in most cases there was a low concentration of 2,3DPG, which enhances oxygen supply to the tissues. These two factors indicate that IUGR infants have a lower capacity for extrauterine adaptation than normal infants.