The Uterine Microbiota

Uterine microbiome has been a subject of interest and research for over two decades. What happens when the embryo implants has fascinated investigators from many different fields including maternal fetal medicine, microbiology, genetics, reproductive endocrinology, and immunology. A perfect relationship between the uterus and the embryo, mediated by a tightly controlled interaction between the embryo and the endometrium, is required for successful implantation. Any factors affecting this communication, such as altered microbiome may lead to poor reproductive outcomes. Current theories suggest that altered microbiota may trigger an inflammatory response in the endometrium that affects the success of embryo implantation, as inflammatory mediators are tightly regulated during the adhesion of the blastocyst to the epithelial endometrial wall. In addition, dysbiosis may change local highly regulated signaling pathways. In this chapter, we will highlight the various microbiome found during the periconceptional period, the microbiome interaction with immunological responses surrounding the time of implantation, its effect on implantation, placentation, and reproductive failure.