Purpose: nucleated red blood cell counts are increased in several hypoxic conditions. The authors aimed to establish if there is a correlation between erythroblast counts in the umbilical vein of newborns and the presence of perinatal hypoxia detected by acid-base balance parameters. Methods: blood samples were obtained from the umbilical vein of pregnant subjects with at least 37 weeks of gestation attended at the Hospital de Alvorada-RS, just before the newborns' first breathing movement. Part of the blood was placed in an EDTA-containing vial and white and red blood cells were analyzed. The remaining amount of blood was aspirated into insulin type syringe previously washed with heparin and pH, pO2, pCO2 and acid-base excess/deficit were analyzed. Slides were also prepared with the panoptic stain for visual identification and count of the erythroblast number. The erythroblast/leukocyte ratio was calculated. Results: of the 158 cases included in the study, 55 were considered free of perinatal hypoxia. In this population, the average erythroblast rate was 3.9% with a standard deviation of 2.8%. The minimum and maximum values were 0% and 10%, respectively. When considering all the cases, the average was 5.7%, with a standard deviation of 5.3%. The minimum and maximum values were 0% and 28%, respectively. Application of Pearson's test for the analysis of the erythroblast rate and acid-base parameters showed a significant correlation for pH and pCO2. The construction of a Receiver Operation Curve showed that for an erythroblast rate of 5%, a 7.25-pH cutoff yields a sensitivity of 54% and a specificity of 56%. Out of the 23 newborns whose normoblast rate was greater than 10%, there was acidemia in 7 (30.4%), 11 (48.7%) were large for gestational age, 3 (13%) were small for gestational age, 7 (30.4%) were anemic, and in 3 (13%) there were no abnormalities. Conclusions: in newborns from uncomplicated pregnancies and deliveries, the erythroblast rate was less than 10%. When it was greater than 10%, a correlation was found mainly with large or small for gestational age, fetal anemia and acidemia.
Normal pregnancy; Fetal well-being; Perinatal hypoxia; Nucleated red blood cells
