Based on the result of the subgroup analysis, there was not any significant difference in the rate of cycle cancellation due to High Risk of OHSS between the GnRH antagonist protocols and the Long GnRH agonist protocol (6 studies; 869 women; RR = 0.59, 95% CI: [0.26 to 1.34]; P = 0.20; I2 = 0%; χ2-P = 0.93; very-low quality evidence; Fig. 10). Here, GNRH1 is linked to ovarian hyperstimulation syndrome.