The findings are in line with the several published studies that have shown Th-1 cytokine or pro-inflammatory cytokine polarization of T helper intracellular cytokines in RIF patients (Kalu et al, 2008 and Kwak-Kim et al, 2003). A previous study also demonstrated the increased ratios of Th-1/Th-2 in the IVF/ICSI−ET failure patients (Liang et al., 2015). However, due to the method restriction, the number of intracellular cytokines of T helper NVP-BGT226 that can be detected simultaneously was limited, and the results were presented in percentages. In contrast, a variety of cytokines in plasma can be measured and analysed quantitatively using the Cytometric Bead Array in this study, as this is an accurate and precise method to measure cytokines in plasma. From the literature, it has been seen that not only do the T cells play an important role in pregnancy, but the innate immune cells are also essential for embryo implantation and angiogenesis (Lee et al., 2011). The maternal immune tolerance is likely to be modulated by both adaptive and innate immunity during pregnancy. The natural killer cells − macrophage, dendritic cell and Treg cell − migrate and increase in the endometrium during the implantation window. Deletion of these cells has deleterious effects on implantation and placental development (Hanna et al, 2006 and Sargent et al, 2006). Previous studies have shown that the circulating and local immune cells communicate with each other, and the systematic immune state may influence local immune cell mobilization and activation (Fujiwara, 2009). Therefore, it is indeed very important that the whole cytokine contents in peripheral blood be analysed at the putative time of embryo implantation.