Haematopoietic indicators of fetal metabolic acidosis.

We aimed to study the haematopoietic response in normal and acidotic deliveries following vaginal and abdominal delivery and to compare this to the surrogate markers of perinatal acidosis. Blood gas analyses, complete blood pictures and erythropoietin assays were performed on umbilical or early neonatal blood samples. Placental sections were examined for the presence of nucleated red blood cells. Perinatal clinical risk factors and major neonatal outcomes were collected. The control population was 78 deliveries where the cord arterial pH was > 7.10. Controls born after labour were compared to those born prior to the onset of labour and to 14 acidotic infants born after labour. Nucleated red blood cells did not increase with labour in the control groups but were significantly higher (p < 0.05) in the acidotic group. Erythropoietin did not significantly change with either labour or acidosis. The predictive values from nucleated red blood cell counts were higher than those from low Apgar scores, atypical cardiotocograph traces, meconium-stained amniotic fluid, erythropoietin and the presence of nucleated red blood cells in placental sections. Nucleated red blood cell counts may be a useful surrogate marker of acidosis where blood gas analysis is unavailable. Further studies are required to examine the timing of the increase of erythropoiesis to help define the onset of the stimulus.