The purpose of this Notice of Funding Opportunity (NOFO) is to support multidisciplinary and innovative intervention research to understand and address maternal morbidity and mortality in the United States, particularly but not exclusively among racial and ethnic minority, socioeconomically disadvantaged, and underserved rural populations, with a focus on understudied healthcare factors. This is a new funding opportunity to advance the goals of the NIH Implementing a Maternal health and PRegnancy Outcomes Vision for Everyone (IMPROVE) Initiative. IMPROVE aims to understand the biological, behavioral, environmental, sociocultural, clinical, and structural factors that affect pregnancy-related and pregnancy-associated severe morbidity and mortality and build an evidence base for improved care and outcomes. The IMPROVE initiative supports research to reduce preventable causes of maternal deaths and improve health for women before, during, and after delivery. It includes a special emphasis on health disparities and populations that are disproportionately affected, such as racial and ethnic minority persons, very young women and women of advanced maternal age, and people with disabilities. The number of awards is contingent upon NIH appropriations and the submission of a sufficient number of meritorious applications.