Reducing Photo-Oxidative Stress in IVF: A Retrospective Analysis of Cycles with Poor Blastocyst Development

<b>Background:</b> The success of in vitro fertilization (IVF) is influenced by multiple patient- and laboratory-related factors, including maternal age, body mass index (BMI), ovarian stimulation, and embryo quality. Laboratory illumination may induce photo-oxidative stress, potentially impairing embryo development and implantation. This study evaluated the clinical impact of introducing a light-protection protocol in an IVF laboratory. <b>Methods:</b> We retrospectively analyzed 2125 IVF cycles with fresh embryo transfer performed at the Assisted Reproduction Centre of the University of Pécs between 1 March 2016 and 30 November 2020. A light-protection protocol was implemented on 1 March 2017, while all other laboratory and clinical parameters remained unchanged. Pregnancy outcomes before and after implementation were compared, with additional subgroup analyses focusing on cycles with low blastocyst-formation rates. <b>Results:</b> After implementation of light protection, overall pregnancy rates increased by approximately 5%; however, this difference was not statistically significant. In contrast, subgroup analyses demonstrated a markedly greater improvement in pregnancy outcomes-up to 37%-in cycles characterized by low blastocyst-formation rates. <b>Conclusions:</b> Although light protection did not significantly improve overall pregnancy rates, the findings suggest a clinically relevant benefit in selected cases with reduced embryonic developmental competence. Minimizing photo-oxidative stress may therefore represent a targeted laboratory intervention to improve IVF outcomes in vulnerable embryo populations.