No Correlation Between Intrauterine Human Chorionic Gonadotropin Infusion and Embryo Transfer Success in Gestational Carriers

Objective Intrauterine infusion of human chorionic gonadotropin (IU hCG) has been suggested by some studies to improve implantation rates after frozen embryo transfer (FET), especially in cases of recurrent implantation failure (RIF) or recurrent pregnancy loss (RPL). In practice, however, IU hCG is administered to patients with a broad range of clinical histories and diagnoses, leading to questions about the scope of clinical utility. This study aims to evaluate the impact of IU hCG on FET outcomes in a sample population of gestational carriers with no known infertility diagnosis. Design Retrospective chart review at a private multi-site fertility center. Materials and Methods The sample consisted of n=112 gestational carriers who underwent FET of a single blastocyst either with 500 IU hCG infused into the uterus before transfer (n=11) or without (n=101). Implantation rate (IR) and clinical pregnancy rate (CPR) were assessed for each group, and results were analyzed using Fisher’s exact test with significance set at p<0.05. Results For IU hCG transfer cycles, implantation was successful in 54.5% (6/11) of cases and clinical intrauterine gestation was confirmed in 36.4% (4/11). For transfer cycles without IU hCG, IR was 65.3% (66/101) and CPR was 54.5% (55/101). Fisher’s exact score was p=0.5181 for IR and p=0.3442 for CPR, with no statistically significant difference observed for either outcome measure. Conclusions Our results fail to show a correlation between IU hCG and IR or CPR in a gestational carrier population, suggesting that IU hCG may not meaningfully enhance odds of FET success in patients with no history of RIF or RPL. Adjuvant therapies such as IU hCG, often experimental and expensive, have become increasingly widespread in an effort to improve outcomes. Further evaluation of IU hCG in patient populations with RIF, RPL, and other diagnoses can make its clinical administration more precise and a more efficient use of practice and patient resources.