Studies in mice also showed an effect of letrozole to increase pigment epithelium-derived factor (PEDF) and to lower vascular epithelial growth factor (VEGF), which might be expected to reduce the risk of ovarian hyperstimulation syndrome (OHSS) with stimulation.
We have shown that ovarian pigment epithelium derived factor (PEDF), a potent antiangiogenic factor, counteracts vascular endothelial growth factor (VEGF) expression and that OHSS is correlated with hCG-induced impaired PEDF to VEGF ratio.