Abstract:Objective: To evaluate its mechanism of inducing the maternal-fetal immune tolerance by studying the effects of Shoutai pills on the expression of Th1/Th2 cytokine andpregnancy in maternal-fetal interfaee of mice with recurrent spontaneous abortion(RSA). Method: The normal pregnancy and RSA model were respectively induced with CBA/J×BALB/c and CBA/J ×DBA/2. The mice with RSA were randomly divided into model group and low, middle and high dose groups of Shoutai pills. The mice were killed in 14 days after administration and embryo resorption rate was counted and their decidual and placental tissues were co-cultured to detect the expressions of IL-4, IL-10, IFN-γ and TNF-α with ELISA. Resuit: The embryo resorption rate of the model group was significantly higher than the normal pregnancy, middle and high dose groups of Shoutai pills could decreased the embryo resorption rate of the mice with RSA (P＜0. 05). All the doses in 3 groups of Shoutai pills could decreased the expression of IFN-γ and TNF-α (P＜0. 05) and there was no obvious difference between normal pregnancy group and all groups of Shoutai pills. Middle and high doses of Shoutai pills could increased the expression of IL-4 and IL-10 (P＜0. 05) and there was no obvious differences between normal pregnancy and high dose group of Shoutai pills. Conclusion: The mechanism about Shoutai pills can change Th1 /Th2 cytokine towards Th2 bias, which induced the maternal-fetal immune tolerance.