title: Reply of the authors.
authors.affiliation: IVF Laboratory, IVI Valencia, Valencia, Spain.
authors.forename: Maria José
authors.initials: MJ
authors.lastname: de Los Santos
mesh_terms: D002970:Cleavage Stage, Ovum / Q000473:pathology*; D010064:Embryo Implantation; D004624:Embryo Transfer / Q000379:methods* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate