Impact of embryo biopsy stage on implantation potential in thalassemias: a propensity score matching study

Abstract Objective: To investigate the impact of biopsy stage on implantation potential of frozen-warmed blastocysts in pre-implantation genetic testing (PGT) cycles for those with thalassemias.Design: Retrospective paired cohort study using propensity score matching (PSM). A time-to-event analysis of Fine-Gray’s analysis was used to compare cumulative live birth rate (CLBR).Setting: Single university-affiliated center .Patient(s): A total of 439 PGT couples were included who underwent PGT for thalassemias between 2015 and 2017.Intervention(s): Two biopsy strategies were evaluated; cleavage-stage biopsy (CB) and blastocyst-stage biopsy (BB).Main Outcome Measure(s): Implantation rate and CLBR.Result(s): A total of 202 ovum pick-up (OPU) cycles from Group CB and 237 OPU cycles from Group BB were included. PSM was conducted for two groups covering characteristics on the OPU cycle and the first frozen-warmed blastocyst transfer (FWBT) cycle , resulting in 140 matched pairs. The implantation rate was significantly lower in the CB group (41.0%, 30.3%, 20.4% in 1st, 2nd and 3rd FWBT cycle respectively, weighted mean 34.2%) than those in the BB group (51.8%, 43.5%, and 40.5% (weighted mean 48.1%), respectively; at P = 0.044, 0.047, 0.039). This was a 28.9% relative reduction ( P = 0.002). The CLBR across three FWBT cycles was significantly higher in the BB group compared with the CB group (80.0% vs. 62.1%, P = 0.032), while the likelihood of LBR was 1.21-fold higher after regression adjustment. Conclusion(s): Cleavage-stage biopsy may partially affect the implantation potential and CLBRs of frozen-warmed blastocysts, compared with blastocyst stage biopsy.