Abstract
PURPOSE: The aim of this study is to compare implantation and live birth rates (LBR) between fresh euploid embryo transfers versus cryo-all cycles with a subsequent embryo transfer into a prepared endometrium. MATERIAL AND METHODS: This is a retrospective cohort study. Patients who underwent an IVF cycle with PGS with trophectoderm biopsy from January 2011 to July 2015 were included. Patients were divided into three groups: "Fresh Only," "Frozen Embryo Transfer ('FET) Only," and "Fresh ET then FET." For "Fresh Only" group (n = 345), PGS results were received within 24 h. For "FET Only" group (n = 514), results were expected after 24 h, and embryos were cryopreserved after biopsy; only FET was performed in this group (no fresh transfer). For "FET with a previous fresh ET" (n = 139) group, patients underwent a fresh ET with a subsequent FET, in which the same cohort of embryos was utilized. The main outcome measures were pregnancy rate (PR), clinical PR, implantation rate (IR), LBR, and early pregnancy loss rate. RESULTS: IRs were statistically higher in the "FET Only" group when compared to the "Fresh Only" group (59.5 vs. 50.6%, p < 0.01) and the "FET with a previous fresh ET" (59.5 vs. 50.6%, p < 0.05). LBR was statistically significant in the "FET Only" group when compared to the "Fresh Only" group (57.6 vs. 46.5 %, p < 0.005) but not when compared to "FET with a previous fresh ET" group (57.6 vs. 47.7%, p = 0.07). CONCLUSIONS: This analysis suggests euploid embryos to be more likely to implant and achieve a LBR in a synthetic FET cycle than in a fresh cycle.