Stressful delivery influences circulating thrombopoietin (TPO) levels in newborns: possible role for cortisol in TPO-mpl binding

The regulation mechanism of circulating thrombopoietin (TPO) level in human newborns remains unknown. In the present study, we examined whether the TP O concentrations in cord blood were influenced by the difference in the del ivery method and the presence or absence of maternal/fetal complications. C ortisol levels were simultaneously measured to assess the adrenal response of fetuses. Both the TPO level and the cortisol level were substantially gr eater in the neonates delivered vaginally with and without the complication s than in those delivered by cesarean section without the complications. Th e binding assay showed that the incubation of mpl(+) /BaF3 cells with corti sol gave rise to a significant decrease in the binding sires of TPO. These results suggest that the stress to the fetuses near the time of delivery af fects the cord blood TPO levels, which may be mediated in part by the actio n of cortisol on the TPO-mpl binding system. (C) 2000 Elsevier Science Irel and Ltd. All rights reserved.