Project Summary/Abstract Background: Cardiovascular disease (CVD) is the leading cause of mortality in both women and men. Preterm delivery (PTD) occurs in 10% of US pregnancies and is associated with twice the risk of long-term CVD morbidity and mortality in mothers. Only 13-17% of the association between PTD and CVD is explained by subsequent development of established cardiovascular risk factors such as hypertension, diabetes, hyperlipidemia and obesity. Our poor understanding of the physiologic pathways from PTD to CVD limits our ability to use PTD as an `early warning system' to better prevent and treat CVD in women. The goal of this project is to expand our understanding of PTD and CVD through discovery and validation of metabolomic signatures and scores among women with a history of PTD, confirming their association with CVD events and performing mediation analysis. We will also examine the association of PTD clinical phenotypes with CVD. Setting: We have assembled an exceptional team with deep expertise in CVD, pregnancy exposures, metabolomics, and biostatistics/ bioinformatics. Investigators on this project have decades of experience studying CVD, pregnancy complications, and metabolomic epidemiological studies. This application will leverage U01-funded infrastructure and biosamples of the Nurses' Health Study (NHS) 2 and 3 cohorts, as well as CVD outcomes and previously measured metabolomic profiles in NHS1 and the Women's Health Initiative. Research Plan: We will measure metabolomic profiles in 1500 women, including 400 women with a history of PTD, and 400 parous women with no preterm deliveries. Metabolomics will be performed at the Broad Institute. Using a robust methodology of discovery and validation, we will: 1) Discover and validate metabolomic profiles and PTD metabolite (M-PTD) scores for midlife women with a history of PTD (NHS2/3). PTD phenotypes to be examined: a) Total PTD; b) Clinical PTD: Preterm prelabor rupture of membranes, spontaneous preterm labor with intact membranes, medically-indicated PTD; c) Timing of PTD: <32 weeks, 32- <37 weeks; Exploratory: Agnostically derived metabolite endotypes of PTD; 2) Examine the association of clinical PTD phenotypes with CVD incidence (NHS2 full dataset); 3) Test the association of M-PTD scores with incident CVD (NHS1, NHS2, WHI) and determine mediation of the observed increased CVD risk from PTD metabolites (NHS2). Relevance to Public Health: CVD is an issue of major public health importance. The proposed analyses have the potential to identify precursors and pathways integral to CVD incidence after PTD, a female-specific cardiovascular risk factor, which may then be used to improve prevention strategies, enhance treatment options, and generate additional testable hypotheses that will guide future CVD research. Our approach leverages decades of prospective data collection in the NHS2 and NHS3 and our strong preliminary data support a high likelihood of success.