[Embryo transfer: a critical step in assisted reproduction].

The advances and development of new procedures and techniques related to embryo development, and its final outcome, the embryo transfer; have increased significantly the pregnancy rate through this reproductive assisted technique. The embryo transfer is probably the last part in in-vitro fertilization programs and the success should be determined through the technical approach and procedure's characteristics. The use and standardization of the current techniques during the embryo transfer process allow increasing the success in pregnancy and implantation rates in a short period of time in the current Assisted Reproduction Programs.