Received July 14, 2025
Accepted February 20, 2026

This study assessed the oxidative-antioxidant status of follicular fluid (FF) in women undergoing in vitro fertilization (IVF), according to their ovarian stimulation response and the morphological characteristics of the recovered cumulus-oocyte complexes (COCs). Redox and inflammatory markers were evaluated in the FF of 77 IVF patients and 15 fertile oocyte donors. Malondialdehyde and nitrite concentrations were elevated in low (LR), normal (NR) and high (HR) ovarian responders compared to controls. Superoxide dismutase (SOD) activity was higher in NR, while glutathione was increased in LR compared to controls. Glutathione peroxidase activity was similar between LR, NR, and controls, but significantly lower in HR. TNF-α was reduced across all groups, while IL-6 was significantly higher in LR and NR compared to controls. In LR, oxidative damage markers were elevated in both grade I and II COCs, along with increased SOD and glutathione, and lower TNF-α compared to controls. LR with grade I COCs showed higher catalase, glutathione, and TNF-α than those with grade II COCs. In NR, grade II COCs showed increased nitrite, catalase, and IL-6, but lower SOD and TNF-α compared to grade I COCs and controls. Embryo quality was associated with COC morphology: in LR, 71.4% of class A embryos originated from grade II COCs, whereas in NR, 81.8% of class A embryos derived from grade I COCs. These results highlight the dynamic interplay between redox balance, inflammation, ovarian response, and oocyte competence, emphasizing the importance of integrating biochemical and morphological markers to improve reproductive outcomes.