Research progress of methods on the assessment of embryonic quality

Selection of embryos with higher potentiality of development has been one of the major challenges in assisted reproductive technology (ART). Morphological scoring method is a general method to evaluate embryonic quality, but it′s not an accurate method due to the personal error. In the past decade, with the development of metabolomics and proteomics, metabolities in embryo culture media such as pyruvate, amino acids, human leukocyte antigen (HLA)-G can be precisely analyzed by newly developed technologies such as Fourier transformation infrared (FTIR) spectroscopy, near infrared spectroscopy (NIR), 1H-proton nuclear magnetic resonance (1H-NMR) spectroscopy, and Raman spectroscopy. Studies have shown that the metabolic profiles vary between pregnancy and non-pregnancy embryos. Thus, noninvasive metabolomics and proteomics might be applied to guide clinical protocol adjustments of in vitro fertilization (IVF) and select transplanted embryo with the best quality. However, chromosome abnormalities in embryo can not be detected by morphological scoring method, metabolomics, proteomics, and genomics can make up for this deficiency. Genomic screening could be conducted to detect non-euploidy embryo before transplantation and thus improve the success rate of ART. This paper reviews the latest research progress of the embryo quality assessment methods. Key words: Embryo research; Preimplantation diagnosis; Reproductive techniques, assisted; Morphogenesis; Metabolomics; Genomics; Proteomics