Bokal et al. [21] found that prolonging the hCG-OPU interval in patients with PCOS improved the expression and action of angiogenic substances such as those of the renin-angiotensin system and vascular endothelial growth factor, enhancing follicular vascularization and, consequently, improving oocyte quality, fertilization competence, and embryo developmental potential. Here, REN is linked to polycystic ovary syndrome.