Humaidan and colleagues allocated females at higher risk of OHSS (follicles ≥11 mm diameter; 15-25 numbers) into 2 groups: ovulation triggering with a bolus of GnRH agonist followed by a single dose of 1500 IU hCG after 35 hr in group A, and receiving 5000 IU hCG by the trigger in group B. Clinical pregnancy rate was 35% in group A and 29% in group B. OHSS rate was 0% in group A and 3.4% in group B (23). This evidence concerns the gene GNRH1 and ovarian hyperstimulation syndrome.