Reasons and Mechanisms of Recurrent Failed Implantation in IVF

Recurrent pregnancy loss (RPL) and recurrent implantation failure (RIF) are serious problems in IVF and ICSI cycles. Different factors are showed to be responsible for these clinical challenges – such as paternal, maternal, embryonic, immunological, infectious, hormonal, and others. In this chapter we have tried to review the available data on reasons for the RIF, and systematize them into: 1) uterine factors; 2) embryo factors; 3) immunological factors; 4) other factors. Interplay between all these factors play a role in RIF, and further investigations are needed to elucidate their significance and interactions – in order to elaborate more definite suggestions or guidelines for the clinicians dealing with artificial reproductive techniques and facing RPL and RIF.