Reduced ovarian response to controlled ovarian stimulation is associated with increased oxidative stress in the follicular environment.

Serum estradiol (E2) level is routinely used to monitor the ovarian response during controlled ovarian hyperstimulation (COH) and the concentration of serum E2 may influence the oocyte quality and pregnancy outcome. However, the knowledge on the association between COH induced serum E2 level, oocyte quality and embryo development is limited. Therefore we investigated the association between serum E2 level, oxidative stress in the follicular fluid and granulosa cells (GCs) response to elucidate the association between E2 level and embryological outcome. In this study, patients (n = 30) undergoing ART were categorized as 'normal responders' (NR, n = 10), 'poor responders' (PR, n = 10) and hyper responders (HR, n = 10). The follicular fluid malondialdehyde (MDA) level was determined. The total RNA extracted from GCs was subjected to analyse the relative abundance of transcripts of stress response genes (P53, caspase 3,8-oxoguanine DNA glycosylase, OGG1 and heat shock protein 70; HSP70) and embryological outcome was noted. Follicular fluid MDA level was significantly higher in PR (p < 0.01) compared NR and HR whereas number of top-quality embryos were significantly lower in PR and HR compared to NR (p < 0.01). The relative expression of P53, HSP70, and OGG1 in GCs was significantly elevated in PR (p < 0.05-0.01). An inverse relationship was established between serum E2 level vs follicular MDA level (r = -0.45; p < 0.01) and follicular MDA level vs. number of top-quality embryos (r = -0.45; p < 0.01). Hence, patients with low serum E2 had elevated oxidative stress in their follicular environment and poor quality embryos implicating the risk of oxidative stress in patients with poor ovarian response.