ABSTRACT
A key step in assisted reproduction is the assessment of embryo viability in order to identify the embryo(s) most likely to result in pregnancy. Currently used embryo assessment systems are largely based on morphology and cleavage rate. While these systems have been pivotal in improving implantation and pregnancy rates and reducing multiple gestations, their precision is still insufficient. The limitations of strategies based on morphology have led to the investigation of adjunctive technologies for non-invasive assessment of embryo viability in assisted reproduction. These include the measurement of glucose, pyruvate, or amino acid levels in the embryo culture media, assessment of oxygen consumption by the embryo, genomic and proteomic profiling, and most recently, analytical examination of the embryonic metabolome. As the number of ART cycles increases worldwide, improvements in the ability to quickly and non-invasively identify the best embryos for transfer become an increasingly more important goal for reproductive medicine.