The feasibility of using histologic placental sections to predict newborn nucleated red blood cell counts

OBJECTIVE: To determine the feasibility of using calculated nucleated red blood cell (RBC) counts from histologic placental slides to predict newborn nucleated RBC counts. METHODS: This retrospective study compared absolute nucleated RBC counts from 24 newborns, diagnosed with fetal distress in labor, with counts calculated from their histologic placental slides. A simple linear regression model was tested with newborn nucleated RBC counts as the dependent variable and calculated placental nucleated RBC counts as the independent variable. RESULTS: The mean +/- standard deviation newborn nucleated RBC count was 4.81 x 10(9) +/- 5.46 x 10(9)/L compared with 1.37 x 10(9) +/- 1.78 x 10(9)/L calculated from placental sections. These data were normalized by logarithmic transformation. A significant linear regression was obtained, r(2) = 0.74, P <.001. The prediction equation obtained was natural logarithm (newborn nucleated RBC count) is equal to 1.002 x natural logarithm (placental nucleated RBC count) + 1.173. CONCLUSION: It is feasible to calculate nucleated RBC counts from histologic slides of the placenta that are predictive of newborn nucleated RBC counts. Further work on more homogeneous groups of subjects is necessary to increase the precision of the method. The placenta could serve as a surrogate source for newborn whole blood nucleated RBC counts around the time of birth.