One study explored the effect of different doses of Letrozole on the incidence of OHSS after oocyte retrieval during IVF in patients with high-risk OHSS, and showed that 2.5 mg, 5.0 mg, and 7.5 mg daily for 5 days can decrease the level of E2 and VEGF to some extent in patients at high-risk for OHSS. Here, VEGFA is linked to ovarian hyperstimulation syndrome.