RESUMEN
Identifying “competent embryos” (those with the greatest potential to develop into normal concept) for transfer to the uterus has been a matter of the highest priority and the subject of both hot debate and ongoing research, since the very inception of human in vitro fertilization (IVF). A thorough literature search was performed to evaluate the correlation between pronuclear morphology, early embryo cleavage speed, cleavage stage embryos, embryo/blastocyst development, “omics”, sHLA-G expression, PGS, and implantation/pregnancy-generating potential in ART. Based on available literature, an array/combination of laboratory observations could assist the scientist with embryo selection. The pronuclear stage morphology, the early embryo division, cleavage embryo stage and quality of the day 3 embryos provides limited guidance. We conclude that use of (invasive) PGS in specific patient populations is appropriate; however, more data are needed to determine its true value for overall impact in ART. Non-invasive selection of blastocysts on day 5 with optimal sHLA-G expression provides a very high degree of confidence to yield a viable pregnancy and potentially reduce multiple gestations.