PROJECT SUMMARY/ABSTRACT The Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units (MFMU) Network was created in 1986 to conduct clinical research studies in obstetrics and perinatal medicine. The MFMU Network consists of a number of major academic clinical centers, a data coordinating center (DCC), and the NICHD. The research studies, randomized trials and observational studies, are aimed at reducing maternal, fetal and infant morbidity related to preterm birth, fetal growth abnormalities and maternal complications, and to provide the rationale for evidence-based, cost-effective, obstetric practice. The MFMU Network structure allows studies to be completed in a more rigorous fashion and more efficiently than individual multi-center projects. To fulfill this mission, the MFMU Network is currently conducting six randomized trials, three observational studies, and two long-term follow-up studies of children. These studies are a reflection of the urgent clinical issues of today including prematurity, maternal pregnancy related morbidity, the opioid crisis and the COVID- 19 pandemic. The DCC is a critically important part of this collaborative effort and a vital part of ensuring these studies are completed on time and with integrity. The overall purpose of the DCC is to make sure that the studies are designed to minimize bias, are conducted using rigorous protocols, and the results analyzed and interpreted appropriately to ensure the validity of the conclusions. The aims of the DCC are to provide scientific and biostatistical expertise in maternal fetal medicine, epidemiology and biostatistics to address the key scientific questions. The DCC will conduct interim analyses for the Data and Safety Monitoring Board, collaborate with MFMU investigators on statistical analyses and the dissemination of study results, and share datasets and resources. The DCC will provide a flexible data management system and collaborate with the MFMU investigators on the conduct and monitoring of each study including training, maintenance of study documents, and reporting to the Steering Committee and Food and Drug Administration. Lastly, the DCC will coordinate communication through both private and public websites, and provide the logistical and administrative support to the overall Network organization necessary to run efficient and productive studies. Through effective organization, communication, and logistical, technical and scientific support, the DCC will continue to provide the framework for the MFMU Network to address the key scientific questions of the ongoing studies.