Umbilical cord blood erythroblast count as an index of intrauterine hypoxia.

The relation of umbilical cord blood arterial pH, Apgar score, leucocyte count, and erythroblast count at delivery with the diagnosis of fetal distress in labour was studied prospectively in three groups of singleton pregnancies delivering at term vaginally (55 infants), by elective caesarean section (39 infants), or by emergency caesarean section for abnormal intrapartum fetal heart rate patterns (55 infants). In the emergency caesarean section group the umbilical cord blood arterial pH was significantly lower and the leucocyte and erythroblast counts were higher than in the elective caesarean section group. Comparison of the emergency caesarean section and spontaneous vaginal delivery groups showed significant differences for pH and erythroblast count, but not for leucocyte count. In the spontaneous vaginal delivery group erythroblastosis was associated with umbilical cord blood pH, whereas leucocytosis was associated with the length of labour. The five minute Apgar score was > or = 7 in all infants. This study suggests that leucocytosis is a non-specific response of the fetus to labour, whereas erythroblastosis reflects fetal tissue hypoxia.