C3 and polycystic ovary syndrome: To find potential markers of oocyte quality, our inclusion and exclusion criteriawere very strict to allow us to identify markers that are exclusive to PCOS-FFwithout overlapping with other pathologies and conditions, such as obesity or OHSS.We hypothesize that the evaluation of fetuin-A, VDBP, complement C3 and 26S proteaseexpression in the FF of PCOS patients undergoing IVF could be associated with oocytequality.