GNRH1 and polycystic ovary syndrome: These results suggest that GnRH-ant has an adverse effect on endometrial receptivity.[63] In the present study, the pretreatment group was treated with GnRH-ant for 3 days in the early follicular phase to achieve pituitary downregulation, by which the disturbed basic endocrine level of patients with PCOS was adjusted and pituitary reactivity was retained.