Normal nucleated red blood cell (nRBC) count
| Reference (first author) | Sample size | nRBCs | Age | Gestation/birth weight | ||
| Naeye10 | 84 | 919 (1425) nRBCs/mm3 | 1 hour | Term, AGA | ||
| 560 (771) nRBCs/ mm3 | 6 hours | |||||
| Green11 | 102 | 400 (1300) nRBCs/mm3 | 12–24 hours | 37–41 weeks, AGA | ||
| Sinha12 | 84 | 2.3 (0.7) nRBCs/100 WBCs | Birth (cord blood) | 2501 and 3500 g | ||
| Shivhare13 | 33 | 4.1 (2.4) nRBCs/100 WBCs | Birth (cord blood) | Term and near-term | ||
| Phelan14 | 83 | 3.4 (3.0) nRBCs/100 WBCs | Birth (cord blood) | ⩾37 weeks, >2700 g | ||
| Hanlon-Lundberg15 | 1,112 | 8.5 (10.3) nRBCs/100 WBCs | Birth (cord blood) | 37–41 weeks1-150 | ||
| Green16 | 26 | 2900 (3600) nRBCs/mm3 | Day 1 | 23–26 weeks | ||
| 37 | 1200 (1800) nRBCs/mm3 | Day 1 | 27–29 weeks | |||
| 86 | 1000 (900) nRBCs/mm3 | Day 1 | 30–32 weeks | |||
| Buonocore17 | 47 | 8521 (1620) nRBCs/mm3 | Birth (cord blood) | 24–27 weeks | ||
| 185 | 4548 (473) nRBCs/mm3 | Birth (cord blood) | 28–36 weeks | |||
| 105 | 1689 (290) nRBCs/mm3 | Birth (cord blood) | 37–41 weeks | |||
| Axt18 | 304 | 3.7 (median) nRBCs/100 WBCs | Birth (cord blood) | 261–289 days | ||
| 6.5 (median)nRBCs/100 WBCs | Birth (cord blood) | 290+ days | ||||
Results are mean (1 SD).
↵1-150 Excludes eight infants with extreme idiopathic increases (>100 nRBCs/100 WBCs) and includes infants with maternal diabetes, growth retardation, birth asphyxia, and other causes known to increase the circulating nRBCs.
AGA, appropriate size for gestational age; WBC, white blood cell.