In ovarian hyperstimulation syndrome (OHSS), a rare but potentially life-threatening condition (for every 55 patients with a long GnRHa protocol, one would be hospitalized because of OHSS), some evidences indicates that the routine use of GnRH-ant instead of GnRHa during ovarian stimulation drastically reduces the relative risk of OHSS (Kolibianakis et al., 2006; Al-Inany et al., 2007; Griesinger, 2010). Here, GNRH1 is linked to ovarian hyperstimulation syndrome.