Received November 17, 2013
Accepted November 17, 2013

INTRODUCTION: The selection of embryos with development potential is essential to the success of in vitro fertilization (IVF). Recent advances in “omics” have enabled noninvasive methods for the selection of embryos, including the study of the secretome by proteomic techniques providing quick information about cell function and embryo physiology. OBJECTIVE: To search, in the human secretome of embryos in IVF, molecules that are important in embryonic viability, which could be relatively easy to observe and allow for the selection of embryos that can result in clinical pregnancies. METHODS AND RESULTS: the proteins present in the secretomes of 94 embryos on days 3 and 5 of development were separated on gel electrophoresis. Using a mass spectrometer MALDI-TOF/TOF a protein, Transthyretin (TTR), was identified, expressed by some embryos from fertilization and in all developmental stages examined, as well as in all blastocysts during culture for 4 hours before transfer. Although all blastocysts that were selected for transfer secreted TTR, the statistical analysis (P=0.576) indicated that there was no relationship between the expression of the TTR and the probability of achieving pregnancy. CONCLUSION: Quantitative differences were observed regarding the expression of TTR in the embryonic secretome, however no such differences might be related to the success or failure of clinical pregnancies.