The Pre- and Early Postnatal Microbiome: Relevance to Subsequent Health and Disease

Abstract

With the advent of the Human Microbiome Project, wherein new high throughput technologies are employed to evaluate the taxonomy and function of microbes residing in various regions of the body, there is increasing recognition of the scope and clinical significance of the intestinal microbiota. The total number of bacterial cells residing in human intestine far exceeds the number of host cells. More than 3 million genes have been identified in this microbiota, which is more than 100-fold of our own human genes. Although commonly thought to be related to disease as pathogens, the majority of microbes of the intestine are commensals and symbionts that benefit the host in terms of nutrition, development of the immune system, and postnatal maturation of the intestine. They perform helpful functions that cannot be performed by the human host itself. This review aims to summarize recently emerging knowledge on the intestine microbiome in the antenatal, perinatal, and postnatal periods. We will limit our discussion to the fetal microbiome, the effects of cesarean delivery versus vaginal delivery, and the relationship of the microbiome to necrotizing enterocolitis, late-onset sepsis, and the developing brain.