Moreover, similarly to the results of the present study, significant differences in luteal phase length (4.16±0.70 days versus 13.63±2.12 days) and in OHSS (0/30 versus 5/30) were observed between donors receiving a GnRH agonist compared with those receiving hCG (Acevedo et al., 2006). Here, GNRH1 is linked to ovarian hyperstimulation syndrome.