Document Type : Review Article
Assessment of embryo quality in order to choose the embryos that most likely result in pregnancy is the critical goal in assisted reproductive technologies (ART). The current trend in human in vitro fertilization/embryo transfer (IVF/ET) protocols is to decrease the rate of multiple pregnancies after multiple embryo transfer with maintaining the pregnancy rate at admissible levels (according to laboratory standards). Assessment of morphological feathers as a reliable non-invasive method that provides valuable information in prediction of IVF/intra cytoplasmic sperm injection (ICSI) outcome has been frequently proposed in recent years. This article describes the current status of morphological embryo evaluation at different pre-implantation stages.