Pregnancy Outcome following Administration of Intravenous Immunoglobulin in Women with Unexplained Recurrent Implantation Failure: A Retrospective Cohort Study.

Background: Recurrent implantation failure (RIF) is a challenging condition affecting approximately 10% of in vitro fertilization (IVF) patients. Despite extensive investigations, up to half of cases remain unexplained. Immune dysregulation has been implicated in RIF, and intravenous immunoglobulin (IVIg) therapy has emerged as a potential treatment. However, the efficacy of IVIg for unexplained RIF remains controversial due to inconsistent study designs and outcomes. The aim of this study was to evaluate the impact of IVIg on pregnancy and live birth rates in women with unexplained RIF. Materials and Methods: A retrospective cohort study was conducted on 136 women with unexplained RIF undergoing frozen embryo transfer (FET) at Yazd Reproductive Sciences Research Institute and Reproductive Medicine Department of Madar Hospital, Yazd, Iran between April 2019 and March 2024. The study included women with unexplained RIF who underwent FET following endometrial preparation using hormonal therapy and received at least three doses of IVIg therapy. Baseline characteristics and pregnancy outcomes were compared. Results: A total of 68 patients were included in each group. The IVIg group had a significantly higher biochemical pregnancy rate compared to the control group [26(38.2%) vs. 13(19.1%), P=0.014]. Although clinical pregnancy, ongoing pregnancy, and live birth rates were numerically higher in the IVIg group, these differences did not reach statistical significance. Conclusion: Our findings suggest that IVIg treatment may be associated with higher biochemical pregnancy women with unexplained RIF. However, larger prospective studies are needed to confirm these results and to assess the longterm effects of IVIg on pregnancy outcomes.