Fig. 1

Detail criteria and selection of the cohort selection. FET: frozen-warmed embryo transfer; NCs: natural endometrial preparation cycles; CE: cleavage embryo; B: blastocyst; CE-CP: cleavage embryo to clinical pregnancy; CE-BP: cleavage embryo to biochemical pregnancy; B-CP: blastocyst to clinical pregnancy; B-BP: blastocyst to biochemical pregnancy