Neonatal nucleated red blood cell count and postpartum complications in growth restricted fetuses

Aims: To study relationships between nucleated red blood cell count (NRBC), persistence of NRBC count elevation and neonatal complications in growth restricted fetuses (IUGR). Methods: Observational study of IUGR neonates (birthweight < 10^th percentile). NRBC's/100 WBC were ascertained in a peripheral blood sample. Subsequent daily samples were analyzed until NRBC's fell < 10/100 WBC. NRBC count and days of NRBC elevation were related to complications (respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotising enterocolitis (NEC), circulatory insufficiency (CI), day 28 oxygen requirement, mortality). Results: 157/298 IUGR neonates (52.7%) had complications, which were associated with a higher NRBC count and persistence of NRBC elevation (12 vs. 189 NRBC's and 1 vs. 4 days; p < 0.0001 respectively). This relationship applied to each complication. Prematurity was the main determinant of RDS, BPD and mortality, while IVH was related to mechanical ventilation, CI to birth-weight percentile and NEC to degree of acidemia. Persistence of NRBC count elevation was a statistical contributor for RDS, CI and mortality, and the NRBC count to day 28 oxygen requirement. Conclusion: NRBC count elevation and persistent NRBC count elevation are associated with perinatal complications in IUGR. Wide ranges in numbers, complex relationships between triggering factors and impacts of other perinatal variables limit the use of NRBC parameters as predictors of complications.