Nucleated red blood cell counts in term neonates with umbilical artery pH < or = 7.00

The purpose of this study was to determine whether nucleated red blood cell (NRBC) counts are elevated in term neonates who have severe fetal acidemia at birth. The neonatal NRBC counts of term (gestational age > or = 37 weeks) neonates with pathological acidemia were compared with those from control neonates who met the following criteria: gestational age > or = 37 weeks, birth weight > or = 2800 g, umbilical artery pH > or = 7.25, and a 5-minute APGAR > 7. Pathological acidemia was defined as an umbilical artery pH < or = 7.0 and a base excess > -12 mEq/L. Twenty-six neonates met all inclusion criteria and were compared to 78 controls. The mean NRBC/100 WBC was 11.9 +/- 13.5 (range 0 to 45) for acidemic neonates compared to 3.9 +/- 2.9 NRBC/100 WBC (range 0 to 11) for control neonates [p <0.001]. Our findings suggest that the onset of hypoxia-ischemia in pregnancies complicated by severe fetal acidemia often begins prior to the intrapartum period.