Abstract
The human body is cohabitated with trillions of commensal bacteria that are essential for our health. However, certain bacteria can also cause diseases in the human host. Before the microbiome can be attributed to disease risk and pathogenesis, normal acquisition and development of the microbiome must be understood. Here, we explore the evidence surrounding in utero microbial exposures and the significant of this exposure in the proper development of the fetal and neonatal microbiome. We further explore the development of the fetal and neonatal microbiome and its relationship to preterm birth, feeding practices, and mode of delivery, and maternal diet.