Abstract: Objective To investigate the effect of SGK1 in decidual stromal cells (DSCs) on Treg/Th17 balance in the peripheral blood lymphocytes of women of reproductive age. Methods DSCs isolated from normal early pregnant women were cultured and identified by immunocytochemistry. The peripheral blood lymphocytes (PBLC) of women of reproductive age were isolated, and co-cultured with DSCs. There were five groups in the current study: a control group, a co-culture group, a SGK1 agonist group, a SGK1 inhibitor group, and a co-stimulation group. The levels of SGK1 were detected by Western blot. The levels of SGK1 mRNA were detected by RT-PCR. The proportion of Treg and Th17 cells was measured by flow cytometry. Results Western blot and RT-PCR results indicated that the levels of SGK1 protein and mRNA in the SGK agonist group were significantly higher than those in other groups (P<0.05). Compared with the co-culture group, the levels of SGK1 protein and mRNA in the SGK1 inhibitor group and the co-stimulation group remarkably decreased (P<0.05), where decreases in the SGK1 inhibitor group were more obvious (P<0.05). According to flow cytometry, the ratio of Treg cells /Th17 cells in the SGK1 agonist group was significantly higher than those in the other four groups (P<0.05). Compared with the control group, the proportion of Treg and Treg/Th17 ratio in in the co-culture group dramatically increased; compared with the co-culture group, the proportion of Treg subsets in the SGK1 inhibitor group and the co-stimulus group was obviously reduced (P<0.05), where decreases in the SGK1 inhibitor group were more obvious (P<0.05). Conclusions SGK1 expressed by DSCs in early pregnancy can affect the proportion of Treg subgroup and Th17 subgroup in peripheral blood lymphocytes。