Bacteria, viruses and one genus of yeasts are a normal part of the uterus before and during pregnancy.[1] The uterus has been found to possess its own characteristic microbiome that differs significantly from the vaginal microbiome. Despite its close spatial connection with the vagina, the microbiome of the uterus more closely resembles the commensal bacteria found in the oral cavity. In addition, the immune system is able to differentiate between those bacteria normally found in the uterus and those that are pathogenic.