PROJECT SUMMARY/ ABSTRACT Despite decades of research, the rates of pregnancy complications, maternal and neonatal morbidity and mortality, and adverse long-term sequalae of pregnancy remain unacceptably high, presenting enormous clinical care and public health needs. The University of North Carolina at Chapel Hill (UNC) Maternal Fetal Medicine Units (MFMU) Network clinical center is committed to addressing these major public health burdens by continuing to contribute to high-quality, definitive multi-site collaborative clinical studies. The UNC MFMU includes UNC Health Care (UNC-Chapel Hill and UNC Rex hospitals) and WakeMed Health (WakeMed Raleigh and WakeMed North hospitals); combined, there were 15,175 deliveries in 2021. UNC MFMU sites have >30 years of MFMU perinatal research experience and include three Level IV and one Level Ill NICU, with established graduate follow-up programs for each hospital system. UNC has an established track record of success as a strong performing, active member of the NICHD MFMU over the last 22 years. The UNC MFMU has completed 22 studies; an additional 9 are currently active. Several currently active studies were initiated during the peak pandemic period; despite this timing, the UNC MFMU maintained excellent recruitment and data quality, demonstrating our perseverance and flexibility to rise to ongoing challenges. We consistently enroll racially, ethnically, and socioeconomically diverse participants, and averaged 6th overall in recruiting from the 2016-2022 cycle. The continued success of the UNC MFMU is supported by our solid infrastructure, ability to successfully recruit from our large diverse patient population, experienced and dedicated team, and culture of clinical research. Further, our expertise and unique strengths in areas including preterm birth, lactation, substance use disorder, disparities, translational research, environmental science, epidemiology, and beyond will prove invaluable to the MFMU Network community. The UNC MFMU is perfectly suited to continue to make substantial contributions to improve obstetric care, with strengths directly aligned to support the MFMU Congressional and public health goals. We will leverage UNC's unique resources to design and implement innovative multi-site, collaborative research proposals to address priority areas as outlined by three overarching aims. Aim 1: Reduce rates of PTB and related morbidity by advancing novel, solution-oriented research. Aim 2: Increase pregnant and lactating people's access to safe and effective therapies to prevent and treat medical and obstetric complications. Aim 3: Develop optimal strategies to protect mothers and babies affected by ongoing and future public health crises, including mental health disorders, substance abuse disorders, environmental hazards, and pandemics. UNC's track record of success for over 20 years, combined with superb infrastructure and personnel and innovative research plans that leverage unique site-spec...