Some studies showed that in the antagonist protocol, when patients with PCOS were added with GnRH-ant after COS initiation, the probability of a premature increase in LH level (26.92%) was higher than that in high responders (15.6%) and the probability of premature ovulation or luteinisation was 2.92%, which occurred in part of large follicles in patients with PCOS. Here, GNRH1 is linked to polycystic ovary syndrome.