GNRH1 and ovarian hyperstimulation syndrome: Advantages of GnRH antagonist as mentioned above, numerous clinical trials and meta-analyses (12, 13) based on the studies comparing GnRH agonist protocol and antagonist protocol have showed a consistent conclusion that GnRH antagonist protocol results in similar live birth rate (LBR) but with significantly lower incidence of any grade OHSS in IVF regardless of treated population (14).