Fresh vs. frozen: pregnancy outcomes and treatment efficacy between fresh embryo transfer vs. untested freeze-all cycles.

Objective: To compare pregnancy outcomes after single blastocyst embryo transfer among patients whose first autologous embryo transfer was either a fresh embryo transfer or a frozen embryo transfer (FET) after a freeze-all, in the absence of preimplantation genetic testing for aneuploidy (PGT-A).

Design: A multicenter retrospective cohort analysis.

Setting: National multicenter fertility practice.