Objective To observe the effect and possible mechanism of tonifying kidney and soothing liver on pregnancy outcome of superovulation rats. Methods Divide 80 female rats of normal estrous cycle into normal group（ n = 20）

model group（ n = 20）

tonifying kidney group（ n = 20） and soothing liver group（ n = 20） randomly. Except the normal group

the other 3 groups were built for controlled superovulation models. From the first day of modelling

tonifying kidney group was given suspension of Bushen Tiaojing Fang（ 补肾调经方

concentration of 2. 78 g / ml）

soothing liver group was given suspension of Xiaoyao Wan（ 逍遥丸

concentration of 0. 162 g / ml）

both 1 ml /（ 200 g · d） by gavage

and the model and normal group were given distilled water of same dose by gavage

for 11 days. Compare levels of estradiol（ E2）

progesterone（ P）

endometrium estrogen receptor（ ER） and progesterone receptor（ PR）. Measure endometrial thickness by HE staining. Observe endometrial morphology and the expression of endometrial pinopodes. Detect endometrial vascular endothelial growth factor（ VEGF） protein and the expression of mRNA. Count the number of encyesis and embryos implantation of each group. Results Compared with normal group

the number of pregnancy and embryos implantation

level of P in serum

the expression of endometrial ER

PR

VEGF protein and mRNA

endometrial thickness and spiral artery all decreased（ P < 0. 05 or P < 0. 01） in the model group. Compared with model group

the number of pregnancy and embryos implantation

level of P in serum

the expression of endometrial ER

PR

VEGF protein and mRNA

endometrial thickness and spiral artery increased in the tonifying kidney group and soothing liver groups（ P < 0. 05）. The difference was not significant between tonifying kidney group and soothing liver group（ P > 0. 05）. Conclusion Tonifying kidney and soothing liver could increase pregnancy rate and the number of embryos implantation of superovulation rats. The underlying mechanism may relate to regulating the sex hormone level

ER

PR and improving tissue morphology and angiogenesis in endometrium.