Implantation Failure: Where to Look Up?

A competent embryo and a receptive endometrium are essential for adequate embryo-maternal cross-talk and successful implantation. However, the majority of women undergoing IVF do not achieve pregnancy after the first embryo transfer, incriminating potential implantation issues. According to statistics, recurrent implantation failure (RIF), for which different definitions have been proposed, is estimated to affect about 10-25% of women undergoing in vitro fertilization (IVF). RIF is a complex condition with overlapping causes. The primary objective of this review is to explore factors such as gamete and embryo quality, chromosomal abnormalities, uterine environment, endometrial receptivity, immune cell biomarkers, and microbiota dysregulation to better understand and overcome RIF challenges. It also highlights the significance of comprehensive evaluations of novel therapies, such as activated autologous platelet-rich plasma (PRP) or peripheral blood mononuclear cell (PBMC) insemination, on pregnancy outcomes in patients with RIF.