The live birth rate using the long GnRH-agonist and multiple-dose GnRH-antagonist are comparable in terms of efficacy, but the incidence of any grade of OHSS and cycle cancellation due to it is significantly lower after pituitary suppression with a GnRH antagonist compared to pituitary downregulation with a GnRH agonist. Here, GNRH1 is linked to ovarian hyperstimulation syndrome.