Objective: To test the hypothesis that lymphocyte and normoblast counts in neonatal blood can be used to identify the time that ischemia and hypoxemia produced cerebral palsy.
Methods: Blood lymphocyte and normoblast counts were analyzed at intervals after birth in 16 neonates for whom we knew the time when antenatal ischemic and hypoxemic brain damage began. These counts were compared with counts from normal newborns, infants with low Apgar scores and no cerebral palsy, and infants with cerebral palsy caused by developmental and other early gestational disorders.
Results: Lymphocyte counts increased to more than 10,000/mm3 and normoblast counts to 2000/mm3 or more within 2 hours after the brain-damaging ischemia and hypoxemia began. Lymphocyte counts returned to normal levels 24 hours after the damaging event took place, and normoblast counts in 24-36 hours. Normal neonates had a mean +/- one standard deviation lymphocyte count of 4430 +/- 1418/mm3 and a normoblast count of 560 +/- 771/mm3.
Conclusion: Following the changing counts of lymphocytes and normoblasts in neonates' blood may accurately identify the time before birth when brain-damaging ischemia and hypoxemia began.