Project Summary/Abstract Group B streptococcal (GBS) infection is the leading cause of infectious neonatal morbidity and mortality in the US. Maternal GBS colonization is the strongest predictor for neonatal GBS infection. African American (AA) mothers and infants are twice as likely to be affected by GBS than their white counterparts. There are currently no effective methods to prevent maternal GBS colonization. Current efforts to prevent maternal-infant GBS transmission during labor center around the administration of intrapartum antibiotics to mothers who screen positive for colonization, which has reduced the number of cases of early onset neonatal GBS sepsis; but this approach does not prevent GBS associated complications that occur prior to labor nor late onset sepsis. Furthermore, the disparity of GBS sepsis between AAs and their white counterparts remains unexplained, uncharacterized, and persistent despite the implementation of intrapartum antibiotics, underscoring the need to further understand factors that shape GBS colonization. Preliminary data suggests that exposure to antibiotics prenatally, which is more common among AA women, may increase the risk for GBS colonization. The advent of metagenomic sequencing of the microbiome offers promise for solving this important microbe-antibiotic clinical puzzle. To date, no studies have systematically examined perinatal antibiotic exposure and/or the dynamics of the microbiome related to maternal GBS colonization throughout pregnancy. In order to better understand the GBS disparity, identify risk and protective factors, this study will examine the oral, gut, and vaginal microbiome of AA pregnant women throughout pregnancy. This nested case-control study will serve to advance the understanding of prenatal risk factors associated with GBS colonization among AA pregnant women by evaluating 16S rRNA and medical record data to accomplish the following Aims: 1) Evaluate the vaginal, gut, and oral microbiome in early and later pregnancy among women with GBS positive vs. negative screening culture. 2) Determine whether prenatal antibiotic exposures predispose to, or protect against, GBS colonization and/or microbiome patterns associated with GBS colonization. Results from this study have the potential to change practice and improve antibiotic stewardship in pregnant populations. The K01 project and mentored training supported by this award were designed for Dr. Wright to establish expertise in quantifying perinatal exposures and microbiome analytic pipelines. Combined with her existing expertise in epigenetics and nursing, the additional training establishes multi-omic expertise as the foundation to sustain an independent, translational program of research focused on developing personalized and mechanistically-targeted interventions to improve health outcomes across the lifespan.