We propose to participate as one of the academic centers in the Cooperative Multicenter Maternal-Fetal Medicine Units Network. The investigators are members of the Departments of Obstetrics, Internal Medicine, and Pediatrics (Neonatology) of the University of Texas Health Science Center at San Antonio. We have the capability of drawing from the large Mexican-American populations of Bexar County, Texas and surrounding counties in our region. We have extensive and recent experience in research design, recruitment of minority populations, and conduct of clinical and basic science studies. Our investigators are experienced in large clinical studies that have been multicentric, randomized, and observational studies. Prior investigations included two studies in which more than 5000 Mexican-American subjects were successfully enrolled. We also have extensive experience in the conduct of NIH-sponsored studies. Although our Department has multiple research interests in clinical obstetrics, it is in the areas of diabetes in pregnancy and prematurity that we have a special expertise. Diabetes is the most common medical complication in pregnancy and is especially common in Mexican-American women. A unique feature of our diabetic program is the conglomerate of experts available in San Antonio to study all aspects of the disease, i.e., epidemiological, clinical, and basic science components. Low birth weight and prematurity have been extensively studied in this Department where our added strength lies in the attention to psychosocial factors in the etiology of disease including design and evaluation of behavioral interventions, and experience with culturally appropriate questionnaires and protocols. With the largest Mexican-American pool of prospective subjects for study in Texas, our center may serve as a facilitator in a collaborative effort across centers that would allow comparison of several clinical conditions in different ethnic groups. At the UTHSCSA, the investigators are enthusiastic at the prospect of participating in the MFMU Network. They have a long record of successful collaboration and anticipate cooperative interaction with the NIH project officer, the Network, and Publication Committee in the implementation, conduct and publication of studies.