Paired analysis of the decidua basalis, decidua parietalis and peripheral blood was used to investigate the percentage of CD8+ T cells and the virus specificity of these cells. Fig. 3a shows that the CD8+ T cells were found to be more abundant in the decidua basalis and decidua parietalis than in the peripheral blood (Friedman test, p = 0.029). In addition, the percentage of tetramer-positive CD8+ T cells was significantly different comparing the decidua basalis, decidua parietalis and peripheral blood (Fig. 3b; Friedman test, p = 0.002). A significantly higher percentage of virus-specific CD8+ T cells was observed in both the decidua basalis and the decidua parietalis compared with mPBL.