How Many Blastocysts Are Needed for PGT-A to Benefit RPL Patients? A 7-Year Retrospective Cohort Study

The efficacy of preimplantation genetic testing for aneuploidy (PGT-A) in couples with unexplained recurrent pregnancy loss (uRPL) may vary according to the number of good-quality blastocysts available. This study is to determine whether PGT-A could improve the cumulative live birth rate (CLBR) among couples experiencing uRPL as the number of high-quality blastocysts increases. A retrospective study involving 1073 couples with uRPL was conducted at a university-affiliated reproductive center. Patients were divided into two groups: 813 participants who underwent PGT-A and 260 participants who underwent conventional in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). A stratified analysis was conducted, which categorized the female participants into three subgroups based on the number of high-quality blastocysts: 1-3, 4-6, and ≥ 7. A binary logistic regression model was used to evaluate the associations between the number of high-quality blastocysts and the cumulative pregnancy outcomes. Among uRPL patients undergoing PGT-A or IVF/ICSI, there were respectively 421 vs. 129 with 1-3 blastocysts, 252 vs. 69 with 4-6 blastocysts, and 140 vs. 62 with ≥ 7 blastocysts. In 1-3 blastocysts subgroup, CLBR was 23.52% after PGT-A vs. 33.33% after IVF/ICSI (adjusted OR 1.005, 95% CI 0.604-1.674, p = 0.984). In 4-6 blastocysts subgroup, CLBR was 53.17% after PGT-A vs. 75.36% after IVF/ICSI (adjusted OR 0.398, 95% CI 0.197-0.802, p = 0.010). In ≥ 7 blastocysts subgroup, CLBR was 73.57% after PGT-A vs. 66.13% after IVF/ICSI (adjusted OR 1.660, 95% CI 0.729-3.799, p = 0.227). In these three subgroups, clinical pregnancy loss rates were all similar between the two treatment methods. In women with uRPL, PGT-A did not improve CLBR, irrespective of the number of high-quality blastocysts available. Routine use of PGT-A in this population is therefore not recommended. Future high-quality randomized controlled trials may better define its appropriate indications.