Cardiovascular disease (CVD) is the leading cause of pregnancy-related mortality and an important contributor to severe maternal morbidity (SMM) in the United States. Both pregnancy-related mortality and SMM have been increasing over the past two decades. This study will examine hospital encounters with a CVD diagnosis in all women of reproductive age (15-49 years), with a subsequent focus on pregnant and postpartum women. More specifically, we will explore relationships between pre- pregnancy CVD, SMM and CVD beyond the postpartum period. We will use data from a family of Maryland state databases that comprise the universe of hospital discharges and emergency Department (ED) visits in the state during 2013-2019. Our primary analytic sample will be comprised of all women of reproductive age with at least one hospital encounter (inpatient or ED visit) in Maryland hospitals during this period; data from only women with one or more delivery hospitalizations during the same period will comprise a secondary analytic sample. We will derive two outcome measures, a primary and an associated CVD encounter measure, as well as SMM and CVD-SMM measures using Centers for Disease Control and Prevention’s ICD-based algorithm. Following exploratory analyses, we will use statistical methods developed specifically for use with longitudinal data to address our specific aims. Of note, survival analysis techniques will be employed to examine time to hospital encounters with CVD diagnosis for the various subpopulations of interest at different times of CVD risk during the period of investigation; and, random effects models adjusted for key (time-varying) patient and hospital characteristics will be fitted to examine whether a previous CVD hospital encounter or a significant pattern of CVD hospital encounter predicts SMM/CVD-SMM during delivery vs. postpartum hospitalizations, and whether SMM/CVD-SMM predicts a subsequent CVD hospital encounter. To our knowledge, this will be the first population-based study to examine hospital encounters with a CVD diagnosis in all women of reproductive age and also the first to explore relationships between pre- pregnancy CVD, SMM and CVD beyond the postpartum period using a longitudinal approach. Our results will be disseminated in the peer-reviewed literature and through presentations at scientific meetings. This pilot study will provide preliminary data for larger grant applications aiming to design interventions to prevent CVD in women over their life course.