In light of previous findings, the purpose of this retrospective cohort study was to examine the differences in pregnancy outcomes of fresh embryo transferred in women with adenomyosis between those undergoing the ultra-long GnRH-a protocol or those undergoing the long GnRH-a protocol and to determine the preferred regimen in women with adenomyosis undergoing IVF/ICSI. This evidence concerns the gene GNRH1 and adenomyosis.