D6 blastocyst transfer on day 6 in frozen-thawed cycles should be avoided: a retrospective cohort study

These results indicate that the suitable timing to transfer D6 blastocysts in FET cycles may be day 5, and D6 blastocyst transfer on day 6 in FET cycles should be avoided. D6 blastocysts transfer and HRT cycles may be associated with a higher EMR.