Blastocyst age, expansion, trophectoderm morphology, and number cryopreserved are variables predicting clinical implantation in single blastocyst frozen embryo transfers in freeze-only-IVF.

Using blastocyst age and before transfer blastocyst expansion and trophectoderm morphology scores to select blastocysts, clinical implantation rates greater than 70% could be achieved for top-scoring blastocysts.