Project Summary Preterm birth (PTB) is the leading contributor to infant mortality and morbidity around the world. Vaginal infection and dysbiosis are known risk factors for PTB. Consequently, there have been intense efforts to understand the relationship between the vaginal microbiome and PTB. A major barrier has been the perplexing observation that while bacterial vaginosis (BV) has been associated with PTB, the diverse bacterial community structure indicative of BV has been associated with PTB in some studies but not others. One likely confounder in understanding this relationship is race, since both BV, a diverse bacterial community structure and PTB are more common among black women than Caucasian women; however, other confounding variables such as yeast may also exist. Yeast often colonize the vagina and treating asymptomatic yeast infections has been shown to reduce PTB. While parturition studies have found no significant associations between PTB and yeast colonization, race and associated bacterial communities were not accounted for. The goal of the proposed research is to simultaneously assess both fungal and bacterial components of the vaginal microbiome to disentangling their relationship with preterm birth. Our hypothesis is that yeast colonization is more common among women with a diverse bacterial community structure and that fungal colonization is associated with PTB within the context of a diverse bacterial community. To test this hypothesis, we will use a novel combination of quantitative PCR and high-throughput sequencing of DNA to accurately quantify fungal and bacteria community diversity and relative abundance. We will apply this approach to vaginal swabs collected from a racially diverse cohort of pregnant women, enabling us to test our hypothesis while controlling for known risk factors. By completing this work, we seek to understand vaginal microbial communities and whether antibiotic/antifungal combination therapies should be considered to reduce risk of PTB.