The impact of cryopreserved sperm on intrauterine insemination outcomes: is frozen as good as fresh?

Frozen sperm utilization might negatively impact cycle outcomes in animals, implicating cryopreservation-induced sperm damage. However, fertilization and intrauterine insemination (IUI) in human studies are inconclusive. This study is a retrospective review of 5,335 IUI [± ovarian stimulation (OS)] cycles from a large academic fertility center. Cycles were stratified based on the utilization of frozen ( , = 1,871) instead of fresh ejaculated sperm ( , = 3,464). Main outcomes included human chorionic gonadotropin (HCG) positivity, clinical pregnancy (CP), and spontaneous abortion (SAB) rates. Secondary outcome was live birth (LB) rate. Odds ratios (OR) for all outcomes were calculated utilizing logistic regression and adjusted (adjOR) for maternal age, day-3 FSH, and OS regimen. Stratified analysis was performed based on OS subtype [ ; ( ): clomiphene citrate and letrozole; and ]. Time to pregnancy and cumulative pregnancy rates were also calculated. Further subanalyses were performed limited to either the first cycle only or to the partner's sperm only, after excluding female factor infertility, and after stratification by female age (35 years old). Overall, HCG positivity and CP were lower in the compared to the group (12.2% vs. 15.6%,