GNRH1 and ovarian hyperstimulation syndrome: However, the total dosage of Gn, duration of Gn stimulation, number of oocytes retrieved, clinical pregnancy rate and incidences of moderate and severe OHSS were significantly lower but the abortion rate was significantly higher in the GnRH antagonist group than in the depot GnRH agonist group (all P < 0.05, Table 2).