Clinical Pregnancy Outcomes Following Blastocyst Transfer Using Media with Different Hyaluronan Concentrations:A Retrospective Cohort Study

Background and Objectives: Hyaluronan-enriched embryo transfer media have been proposed to improve implantation and reproductive outcomes; however, their clinical benefit remains uncertain, particularly in frozen embryo transfer cycles. This study aimed to compare clinical pregnancy outcomes following blastocyst transfer using two commercially available media with different hyaluronan concentrations. Materials and Methods: This retrospective cohort study included 421 blastocyst transfer cycles performed at a single IVF center between November 2024 and April 2026. Seventy-two cycles used a hyaluronan-enriched transfer medium (EmbryoGlue), and 349 used a medium with a lower hyaluronan concentration (SAGE 1-Step). The primary outcome was clinical pregnancy, defined as an intrauterine pregnancy with fetal cardiac activity. Exploratory multivariable logistic regression was performed adjusting for maternal age and transfer type. Results: Clinical pregnancy occurred in 21/72 cycles (29.2%) in the hyaluronan-enriched medium group and 127/349 cycles (36.4%) in the lower-hyaluronan medium group (p = 0.30). The use of the hyaluronan-enriched medium was not significantly associated with clinical pregnancy after adjustment for maternal age and transfer type (aOR = 0.77, 95% CI: 0.44–1.34, p = 0.352). Increasing maternal age was associated with lower odds of clinical pregnancy (aOR = 0.95 per year, 95% CI: 0.91–0.98, p = 0.002), whereas transfer type was not (aOR = 1.14, 95% CI: 0.59–2.21, p = 0.688). No significant differences were observed in either maternal age subgroup. Conclusions: In this predominantly frozen blastocyst-transfer cohort, no statistically significant difference in clinical pregnancy rates was observed between the hyaluronan-enriched and lower-hyaluronan transfer medium groups. Given the retrospective, non-randomized design, differences in medium composition beyond hyaluronan concentration, and potential residual confounding, these findings should not be interpreted as evidence of equivalence or as demonstrating the absence of a clinically relevant effect. Prospective randomized studies evaluating live birth are warranted.