Clinical and perinatal outcomes of fully hatched versus not fully hatched blastocysts.

Objective: To compare the clinical and perinatal outcomes following the transfer of fully hatched (FH) and not fully hatched (NFH) blastocysts in assisted reproductive technology.

Methods: This study enrolled women undergoing their first oocyte retrieval cycle with a freeze-all strategy, provided that they had at least one transferrable embryo. Patients were classified into preimplantation genetic testing for aneuploidy (PGT-A) cycles and non-PGT cycles, including thawed blastocysts (thawed-blast) and blastocysts cultured from thawed day 3 embryos (blast-thawed-d3). We compared pregnancy and perinatal outcomes following the transfer of an FH blastocyst or an NFH blastocyst. The primary outcome was the live birth rate. In PGT-A cycles, multivariate logistic and linear regression models were used to adjust for covariates. In thawed-blast and blast-thawed-d3 cycles, baseline characteristics between the FH and NFH groups were balanced via propensity score matching.

Results: In PGT-A cycles, no significant differences were detected between the FH and NFH groups in implantation rate (67.5% vs. 66.5%, adjusted odds ratio [aOR] 1.17; 95% confidence interval [CI] 0.98-1.39), miscarriage rate (15.0% vs. 14.1%, aOR 0.95; 95% CI 0.72-1.27), live birth rate (56.5% vs. 56.4%, aOR 1.13; 95% CI 0.96-1.34), or perinatal outcomes. In thawed-blast and blast-thawed-d3 cycles, no significant differences were observed in pregnancy and perinatal outcomes between the FH and NFH groups.

Conclusions: In both PGT-A and non-PGT cycles, pregnancy and perinatal outcomes following transfer of FH and NFH blastocysts were comparable.