Chen, ⁠Vittor Pelanda

Abstract Introduction Many couples who do not achieve pregnancy with intrauterine insemination (IUI) subsequently pursue in vitro fertilization (IVF). While the impact of semen parameters on IUI outcomes is well established, it remains unclear whether characteristics of sperm following IUI preparation predict future IVF success. Many couples who do not achieve pregnancy with intrauterine insemination (IUI) subsequently pursue in vitro fertilization (IVF). While the impact of semen parameters on IUI outcomes is well established, it remains unclear whether sperm characteristics following IUI preparation predict future IVF success. Here we study a novel, clinically accessible marker of sperm quality – percent change in total motile sperm (TMS) after IUI sperm wash-that may predict fertilization and blastulation outcomes in subsequent IVF cycles. Objective This aims to evaluate the association between changes in total motile sperm (TMS) after IUI sperm wash and fertilization rates in subsequent IVF cycles.This study aims to evaluate the association between changes in TMS after IUI sperm wash and fertilization and blastulation rates in subsequent IVF cycles. Methods In this retrospective study, we identified couples at a single academic center who failed to achieve a live birth following IUI and subsequently underwent IVF with the same partner. To minimize confounding, only couples with a diagnosis of unexplained infertility or male factor infertility were included. In patients who underwent multiple IUIs (median of 2), the cycle with the greatest percent decrease in TMS was selected for analysis. Additional predictive variables of female partner age, male partner age, pre-wash TMS, and insemination method were assessed. A stepwise variable selection method was utilized to identify predictors of fertilization rate and complete blastulation failure, with linear and logistic regression models of selected variables developed, respectively. Results From the cohort of 388 couples, the median fertilization rate during IVF was 56% (IQR 43%–70%). Thirteen percent of couples experienced complete blastulation failure. Change in TMS was selected as a predictor of both fertilization rate and blastulation failure. A 10% greater decline in TMS after IUI sperm wash was associated with a 1.02% lower fertilization rate (p=0.052), after adjustment for insemination method. A 10% greater decrease in TMS was associated with a 1.22-times (95% CI 1.04, 1.48) increased odds of blastulation failure (p=0.023) after adjusting for female partner age. Conclusions A greater percent decrease in TMS following IUI sperm wash is associated with lower fertilization rates and a higher odds of blastulation failure in subsequent IVF cycles. These findings support the hypothesis that significant declines in TMS after sperm preparation may reflect underlying sperm quality defects not detected by routine semen analysis, yet still relevant to fertility outcomes. By identifying sperm quality issues not apparent on standard semen analysis, these findings offer a new tool for risk stratification and counseling of couples transitioning from IUI to IVF. Disclosure No