GNRH1 and endometriosis: Two non-randomized studies comparing PPOS versus GnRH antagonist protocols reported similar numbers of retrieved oocytes in both groups (Guo et al., 2020; Mathieu d’Argent et al., 2020), suggesting that the PPOS protocol could serve as a viable alternative for women with endometriosis, particularly when a fresh embryo transfer is not planned; the rationale behind using progestins lies in their comparable efficacy to GnRH antagonists in preventing premature LH surges.