However, as previously mentioned, the use of a GnRH antagonist combined with ovarian stimulation with gonadotropins in women with PCOS and the induction of final ovarian maturation with a GnRH agonist with subsequent embryo cryopreservation are more effective strategies to prevent OHSS regardless of metformin use 33. This evidence concerns the gene GNRH1 and ovarian hyperstimulation syndrome.