Background: The Black-White disparity in birth outcomes in the United States remains embedded. The World Health Organization (WHO) defines low birth weight (LBW) as birthweight less than 2500 grams/5.5 pounds or below the 10th percentile for gestational age. LBW is a frequent marker of poor maternal/infant health outcome. A reduction in the incidence of LBW is a major public health initiative in the US. Objective: The objective of the study was to determine the magnitude of risk for low birth weight, defined in this study as neonatal birth weight less than 2500 grams, in relation to combined maternal alcohol and tobacco use. The impact of the combined risk taking behaviors was explored to determine their role in contributing to the racial disparity in low birth weight within the context of the Black woman's cumulative socioeconomic disadvantage and exposure to chronic stressors of the urban environment.

Methods: Design: A population-based study of singleton births born to US -born Black and White women delivered in the USA in 2003. Sample: The natality files produced by the National Center for Health Statistics (NCHS) of the U.S. Department of Health and Human Services. Questions: This study addressed the following questions:
(1) What is the incidence and relative risk for LBW in relation to combined maternal alcohol and tobacco use? (2) Does LBW increase with the advancing maternal age of the Black woman? (3) Are there any similarities in maternal age, highest educational attainment by the mother, or population of the place of maternal residence within the Black and White LBW groups reporting the highest incidence of tobacco and/or alcohol use? Theoretical Framework: the weathering hypothesis described by Arlene Geronimus which posits the health of African-American women may begin to deteriorate in early adulthood as a physical consequence of cumulative socioeconomic disadvantage, served as the underpinning for exploring the study variables.

Analysis: Secondary analysis of this data set was performed with SAS V9. Logistic regression was used to calculate the relative risk of the investigational variable (LBW) while controlling for race, age, smoking and drinking status, and geographic place of residence (city population).

Results: Black non-Hispanic women who were both tobacco and alcohol users were 3.2 times more likely to have a LBW neonate and White non-Hispanic women were 2.9 times more likely to have a LBW neonate than non-users. Despite the increased odds for having a LBW infant with concomitant substance abuse of tobacco and alcohol, the rate in the Black women was 2.2 times more than the White women. This risk taking behavior clearly increases the incidence of LBW, but affects both races in a similar fashion.

Future Research: The Black-White disparity in low birth weight is a complex research question with little consensus regarding the exact medical etiology or the pathways through which social environmental factors contribute to the disparity.

This dissertation, in light of the support of the major construct of the weathering hypothesis of advanced maternal aging of the Black woman, suggests that the direction for future research must examine the complex interplay of the multiple factors of the environment, genetics, and stress. Interdisciplinary collaboration among health researchers, urban planners, and policy experts will be the key to understanding what measures must be employed to eliminate the Black-White disparity in low birth weight.