A study of over 2,000 women undergoing frozen embryo transfers found that adding a short course of a GnRH agonist (the peptide gonadorelin) to standard hormone replacement therapy boosted live‑birth rates in women who had a thin uterine lining and had previously been treated for chronic endometritis. The benefit was seen only when the GnRH agonist was combined with hormone therapy, not when hormone therapy was used alone.

Both thin endometrium and chronic endometritis (CE) have adverse effects on pregnancy outcomes. Recently, it is often believed that downregulating gonadotropin-releasing hormone agonists (GnRH-a) might enhance endometrial receptivity and raise the chance of a successful pregnancy. A retrospective analysis of 2102 infertile women who received frozen embryo transfer (FET) cycles was carried out. Standard antibiotic treatment was administered to women with CE, and a follow-up biopsy verified that the CE had been cured. Subsequently, these patients received endometrial preparation, and FET was performed. This study systematically evaluated the impact of three different endometrial preparation strategies on pregnancy outcomes in FET cycles. Potential confounders were controlled through 1:1:1 propensity score matching (PSM) and multivariable logistic regression analysis based on prematched data. There were 117 cycles in each group after matching and all baseline characteristics were balanced with no significant differences between the groups. In patients with thin endometrium and cured CE, the LBR in the GnRH-a-HRT group was significantly increased compared to both the HRT group and the NC group. The results after matching were highly consistent with the multivariable-adjusted findings from the pre-matching analysis. This study indicates that GnRH-a-HRT protocol improves the LBR in patients with thin endometrium and cured CE compared to the HRT and NC protocols in FET cycles.