Preterm birth is a major cause of perinatal morbidity and mortality but its causes are only poorly understood. The problems are particularly significant for African-Americans, who are twice as likely as Caucasians to experience the death of an infant under one year old and to have a baby born preterm. While some evidence implicates psychosocial stress and the related autonomic nervous system dysfunction as a pathophysiologic factor, little is known about their roles in adverse pregnancy outcomes. The overall aim of this application for an exploratory grant is to examine the role of the ANS, psychosocial stress, and racial differences as they relate to duration of gestation and birth weight. From 1996 to 2001, data were collected from 683 pregnant military women stationed at Lackland Air Force Base. In 390 of these subjects, heart rate and blood pressure responses to standard laboratory stressors were measured during the second trimester to determine if responsiveness to these stressors predicted adverse birth outcomes. We used this opportunity to collect, digitize, and archive continuous electrocardiographic, blood pressure, and respiratory waveforms for later analysis of heart rate and blood pressure variability and baroreflex sensitivity, indices of autonomic regulation that are considerably more sensitive than heart rate and blood pressure. Support for analysis of the autonomic data was not provided by the Department of Defense project. These archived data provide us with an unprecedented opportunity to conduct exploratory analyses using more sensitive indices to characterize autonomic regulation of the cardiovascular system at rest and in response to standardized laboratory stressors during pregnancy in a large sample of military women who are homogeneous with respect to many potentially confounding variables relevant to birth outcomes, e.g., physical health, employment status, health behaviors, and access to prenatal care. Using this existing dataset, we propose to explore the role of the autonomic nervous system in premature delivery and low birth weight in general, and more specifically, how stress-related autonomic dysregulation may contribute to the substantially elevated risk of poor birth outcomes in African American women. ? ? ?
