Effects of the Zishen Yutai Pill on live births compared with placebo among infertile women with frozen-thawed embryo transfer cycle: A multicentre double-blind randomized controlled trial

BACKGROUND: Zishen Yutai Pill exhibited clinical benefit to infertile women undergoing fresh embryo transfer cycles, improving their pregnancy outcomes. However, as the endometrial environment in frozen embryo transfer (FET) is different from fresh cycles, the effects of ZYP on fresh embryo transfer could not be generalized to FET. OBJECTIVE: We aimed to explore the effects of ZYP on live birth rate in women's FET cycles. METHODS: This multicentre, double-blind, placebo-controlled, randomized study was conducted at 11 reproductive medical centres in China. Women were recruited and randomly assigned to ZYP or placebo intervention (5 g once, 3 times per day) around the time of FET. The live birth rate was set as the primary outcome. Secondary outcomes included implantation rate, biochemical pregnancy rate, clinical pregnancy rate, pregnancy loss rates. Data was analyzed based on the intention-to-treat principle, with per protocol analysis as sensitivity analysis. RESULTS: Between December 2017 and April 2019, 934 women were screened, of whom 880 met all eligibility criteria and were allocated to ZYP (n=441) or placebo (n=439). In ITT analysis, the live birth rates were 38.32% (169/441) in ZYP group and 32.57% (143/439) (absolute difference 5.75%, 95%CI [-0.57%, 12.00%], OR 1.29, 95%CI [0.98, 1.70], P=0.08). The intervention of ZYP did not result in significantly differences in all secondary outcomes compared with placebo (all P>0.05). Similar trends were observed in PP analysis. In post hoc analysis, ZYP resulted in higher rates of live birth than placebo among women in specific subgroups, i.e., with miscarriage history (39.23% vs. 26.45%, P=0.01) or advanced maternal age (33.93% vs. 21.85%, P=0.04). CONCLUSION: In infertile women undergoing FET cycle, intervention with ZYP led to a trend of live birth rate increment compared with placebo, but without statistical significance. However, women with miscarriage history and advanced age could experience possible benefits from ZYP intervention. REGISTRATION: ChiCTR-INR-17010809 (http://www.chictr.org.cn).