Endometrium Ratio between Fresh and Frozen Cycles is Associated with Embryo Implantation

Introduction:
This study investigated the difference between endometrial thickness in the frozen embryo transfer (FET) cycle and the preceding fresh stimulated cycle as a potential predictor for clinical pregnancy in women with thin endometrium.

Methods:
We retrospectively analyzed 393 cycles in 257 women (age<43) with suspected thin endometrial thickness

Results:
Clinical pregnancy and live birth rates in FET cycles were higher in women with endometrial thickness of ≥7 mm (29.3% vs 15.2%, p=0.007 and 18.8% vs. 8.7%, p=0.025). Embryo implantation did not occur in FET endometrial thickness

Conclusion:
Endometrial thickness in FET cycle normalized to the preceding stimulated cycle (ETfrozen/fresh) is associated with embryo implantation. This ratio may constitute a novel predictor of embryo transfer success in women with thin endometrium (