PROJECT SUMMARY In the United States (US), there are nearly 4 million births per year, and childbirth is the leading indication for hospitalization. Correspondingly, the prevention of preterm birth and maternal morbidity are important clinical and public health goals. In addition, adverse maternal and neonatal outcomes are sources of major health inequities in the US; improvements in obstetric care, therapeutic interventions, and screening or diagnostic strategies have the potential to improve outcomes for all individuals, and particularly those from diverse populations. Innovative and transformational obstetric research is required to achieve these goals, making rigorous, multi-site clinical trials and observational studies designed to improve obstetric outcomes of the utmost importance. The Maternal-Fetal Medicine Units (MFMU) Network, by creating a multi-site research infrastructure, is an important mechanism to effectively accomplish this goal. The Northwestern Study Center, through its use of innovative recruitment and study designs, strong scientific leadership, outstanding academic productivity, and a large and diverse patient population available for research, has been a productive member of the MFMU Network since 2001. The Northwestern Study Center is composed of two institutions – Northwestern University and NorthShore University HealthSystem – that have a two-decade history of successful collaboration, including within the MFMU Network. The combined volume of birthing individuals receiving care at these sites is 19,000 births; a high volume of these births occur to individuals who are from diverse, underrepresented populations or at high risk for adverse outcomes. In this application, we propose that the Northwestern Study Center continues to participate in the NICHD MFMU Network. A team of experienced clinical researchers (Lynn Yee, MD, MPH; Michelle Kominiarek, MD, MS; Beth Plunkett, MD, MPH; Gail Mallett, RN), who have longstanding and nationally-recognized expertise with obstetric clinical research in general and the MFMU Network specifically, lead this renewal application. With strong institutional support, a uniquely collaborative research environment, and prior successful participation in and leadership of multi-site clinical trials, the Northwestern Study Center will continue its significant contributions to the MFMU Network’s goals through robust enrollment of socioeconomically diverse individuals and the completion of novel and important studies.