Erythropoietic progenitor cells in human fetal blood

Ultrasound guided fetal blood sampling performed for diagnostic purposes allowed us to determine the circulating level of erythropoietic progenitor cells (BFU-E) from the 19th to 30th weeks of gestation. Normal fetal blood showed a mean of 160 BFU-E (+/- 107) per 10(5) nucleated cells during the second and third trimesters of pregnancy, which is 3 times higher than in cord blood at birth and 10 times higher than in adult bone marrow. These findings are in keeping with an important circulation of hematopoietic progenitors during fetal life.