GNRH1 and ovarian hyperstimulation syndrome: As the exogenous hCG trigger appears to be the major contributor to OHSS, presumably due to its longer half-life, there has been an effort to develop stimulation protocols that avoid its use, the most effective of which appears to be a GnRH antagonist cycle with a GnRH agonist (GnRHa) trigger for final follicle maturation [7–10].