Association between endometrial echo on transfer day and pregnancy outcomes in thawed embryo transfer: a retrospective cohort study across different preparation protocols

Non-homogeneous endometrial echo on the transplantation day was associated with a decreased clinical pregnancy rate of FET. The endometrial preparation protocol of the NC and GnRHa+HRT cycle can improve homogeneous endometrial echo. In FET, clinicians should develop a personalised endometrial preparation protocol based on patients' situations.