GNRH1 and ovarian hyperstimulation syndrome: Filicori et al. confirmed that low-dose hCG can be used to stimulate the growth of large follicles and accelerate the demise of small follicles (<10 mm diameter) when administered during the mid-follicular or late follicular phase of ovarian stimulation with the gonadotropin-releasing hormone agonist (GnRH-a) protocol or the GnRH antagonist (GnRH-ant) protocol (3–7), resulting in a lower incidence of OHSS (8).