Objective: To investigate the relationship between erythropoietin concentration in umbilical venous blood and clinical signs of fetal hypoxia.
Methods: We measured erythropoietin concentrations in umbilical venous blood from 200 consecutively born neonates using an enzyme-linked immunosorbent assay (ELISA) with two monoclonal antibodies. Results were available within 6 hours. Inter-assay variation was 8.5% and the mean intra-assay variation was 14.2%.
Results: Using a multiple regression analysis, we found that the erythropoietin concentration correlated significantly (P < .01) with fetal growth retardation and umbilical acidosis but not with gestational age, meconium-stained amniotic fluid (AF), abnormal fetal heart rate (FHR) pattern, or Apgar score at 5 minutes. Median erythropoietin concentrations were 25.1 mU/mL in infants with no risk factors or complications during pregnancy and delivery (n = 19), 25.8 mU/mL after complicated pregnancy (n = 95), 50.6 mU/mL with meconium-stained AF (n = 12), 44.7 mU/mL with abnormal FHR pattern (n = 40), 47.8 mU/mL with both stained AF and abnormal FHR pattern (n = 10), and 72.6 mU/mL with umbilical acidosis (n = 24). The median erythropoietin concentration increased significantly with decreasing pH and with increasing base deficit in umbilical arterial blood. The erythropoietin concentration in umbilical venous blood (cutoff value 50 mU/mL) discriminated between infants with no clinical signs of fetal hypoxia and those with umbilical acidosis with a sensitivity of 75% and a specificity of 90%.
Conclusions: Elevated erythropoietin concentrations in umbilical venous blood indicate prolonged fetal hypoxia. The ELISA technique might be a useful tool for determining the exact time course of erythropoietin concentrations in fetal hypoxia.