Association of stress during delivery with increased numbers of nucleated cells and hematopoietic progenitor cells in umbilical cord blood

Objective: Umbilical cord blood can be used as a source of bone marrow repopulating cells for allogeneic stem cell transplantation. Large variations in the frequencies of white blood cells and hematopoietic progenitor cells have been found for umbilical cord blood. These variations may be due in part to specific circumstances during labor and delivery. Study Design: In this study we analyzed the relationship between stress factors occurring during parturition and the frequencies of nucleated cells, leukocyte subsets, CD34+ cells, and hematopoietic progenitor cells, as determined in semisolid medium cultures of umbilical cord blood. Results: We observed that a prolonged first stage of labor resulted in increases in the numbers of nucleated cells, granulocytes, CD34+ cells, and hematopoietic progenitor cells in umbilical cord blood. Evaluation of parameters that indicate stress of the infant during delivery demonstrated higher numbers of nucleated cells, granulocytes, CD34+ cells, and hematopoietic progenitor cells in umbilical cord blood from children with lower venous pH. Conclusion: Longer duration stress during delivery increased the numbers of nucleated cells, granulocytes, CD34+ cells, and hematopoietic progenitor cells, possibly by causing mobilization of various cell populations by endogenous cytokines. As long as umbilical cord blood harvesting does not interfere with the delivery, umbilical cord blood collected after stressful deliveries may provide optimal units for hematopoietic stem cell transplantation. (Am J Obstet Gynecol 2000;183:1144-51.)