In 113 patients with at least 25 follicles ≥11 mm on day of trigger, mean ovarian volumes were (hCG 168.6, GnRHa 98.2, kisspeptin 66.9 ml), rates of mild to severe OHSS (hCG 87.5%, GnRHa 33.9%, kisspeptin 16%) and rates of moderate to severe OHSS were (hCG 37.5%, GnRHa 1.7%, kisspeptin 0%). Here, KISS1 is linked to ovarian hyperstimulation syndrome.