Nucleated red blood cells in polycythemic infants

OBJECTIVE: This study was undertaken to evaluate whether the absolute nucleated red blood cell (RBC) count is elevated in term, appropriate-for-gestational-age (AGA) polycythemic infants. STUDY DESIGN: We compared absolute nucleated RBC counts taken during the first 12 hours of life in term, AGA infants with neonatal polycythemia (n = 29), and in control, nonpolycythemic infants (n = 37). We excluded infants of women with diabetes, hypertension, and alcohol, tobacco, or drug abuse, and those with fetal heart rate abnormalities or low Apgar scores, hemolysis, blood loss, or chromosomal anomalies. RESULTS: There were no differences between groups in birth weight, gestational age, or other demographic or perinatal factors. The hematocrit, RBC count, and absolute nucleated RBC counts were significantly higher and the platelet counts significantly lower in the polycythemic group. Regression analysis that included Apgar scores and gestational age showed a significant correlation of absolute nucleated RBC count with the polycythemia status only (P = .017). CONCLUSION: At birth, term AGA polycythemic infants have increased indices of active erythropoiesis. We speculate that this finding is suggestive of subtle fetal hypoxemia.