RELATIONSHIP BETWEEN NEONATAL NUCLEATED RED-BLOOD-CELL COUNTS AND HYPOXIC-ISCHEMIC INJURY

Objective: To determine if nucleated red blood cell counts (RBC) are d ifferent in infants who develop intraventricular hemorrhage and perive ntricular leukomalacia in the first week of life and in those who do n ot. Methods: Nucleated RBCs were obtained from 441 infants weighing mo re than 499 g and less than 1751 g. Neonatal cranial fontanel sonograp hy was performed on days 3 and 7 of life, and neonates were divided in to those with normal and abnormal sonographic findings. The nucleated RBCs were compared between these groups and between normal and abnorma l groups matched for birth weight and gestational age. Results: Mean g estational age, birth weight, birth weight percentile, Apgar score, re spiratory distress syndrome and mortality were different between the i nfants with normal and abnormal ultrasound findings. The nucleated RBC s (per 100 white blood cells) were not different (40.5 +/- 126.8 versu s 41.8 +/- 71.7, t = 0.09, P =.9). When we controlled for gestational age and birth weight, there was no significant difference between nucl eated RBCs in those with normal and abnormal sonography (54.3 +/- 206. 5 versus 41.4 +/- 72.0, t = 0.56, P =.6). In growth-restricted neonate s, there was a significant increase in nucleated RBCs regardless of wh ether growth restriction was defined as tenth percentile or less, 25th percentile or less, or 50th percentile or less, even when we controll ed for gestational age. Conclusion: Nucleated RBCs are not different i n preterm infants with or without intraventricular hemorrhage and peri ventricular leukomalacia, even when one controls for gestational age a nd birth weight. There are significant elevations in nucleated RBCs in growth-restricted fetuses. Birth weight percentile must be considered when using nucleated RBCs as a marker of intrauterine hypoxia.