Socioeconomic Vulnerabilities and Disparities in Preterm Birth Rates: Analysis of Mississippi Counties POPULATION BRIEF

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1 POPULATION BRIEF The University of Mississippi Center for Population Studies & State Data Center of Mississippi Socioeconomic Vulnerabilities and Disparities in Preterm Birth Rates: Analysis of Mississippi Counties John J. Green, PhD The University of Mississippi Center for Population Studies Katie Kerstetter, MPP George Mason University with Molly Phillips, MPH, MSW; Sarah Gayden Harris, BA; Sannie Snell, LMSW, MPH; Debarashmi Mitra, PhD March 2013 Overview Maternal and child health are key indicators of the health and wellbeing of a population. Poor birth outcomes such as preterm birth (<37 weeks of gestation), low birth weight (< 2,500 grams), and infant death are major issues of concern. As reported in a previous Population Brief, preterm birth is a risk factor for other poor health outcomes. 1,2 For this reason, the Right! from the Start project (a collaborative initiative between Women and Children s Health Initiatives and the Community Foundation of Northwest Mississippi) focuses on building awareness of preterm birth, advocating for the needs of vulnerable children and families, and providing action-oriented education to improve services provided to families. While infant mortality rates in Mississippi have declined over the past several decades, these declines have leveled off in recent years, and preterm birth rates have increased. At the same time, racial disparities in preterm birth rates between white and black women of all ages have remained fairly continuous. 3 This Population Brief investigates county-level variation in preterm birth rates, and explores how these patterns might be influenced by socioeconomic conditions in the spaces where people live, learn, and work. We find that counties with a lower level of median household income, a higher percentage of families living in poverty, and a higher level of income inequality are significantly more likely to have higher rates of preterm birth. These patterns fit with research literature demonstrating that women who lack access to flexible, health-promoting resources and who experience cumulative exposure to stress and adverse socioeconomic circumstances are more likely to experience a preterm birth than women in more advantaged circumstances. Our analyses suggest that local, regional, and statewide efforts to increase household incomes, reduce poverty, and lower inequality are important additions to initiatives focused on individuals in order to influence overall preterm birth rates in Mississippi. Additionally, this work emphasizes the continued presence of racial disparities in health outcomes. 1 Green, John J., Sarah Gayden Harris, Molly Phillips, and Sannie Snell Exploring Trends and Disparities in Preterm Births in Mississippi. Population Brief. University of Mississippi Center for Population Studies. 2 Williamson, Dhelia M., Karon Abe, Christopher Bean, Cynthia Ferré, Zsakeba Henderson, and Eve Lackritz Current Research in Preterm Birth. Journal of Women s Health 17(10): Green, et al

Methods We obtained county-level preterm birth data for this analysis from the Mississippi Department of Health through the Mississippi Statistically Automated Health Resource System.

2 Methods We obtained county-level preterm birth data for this analysis from the Mississippi Department of Health through the Mississippi Statistically Automated Health Resource System. The preterm birth rate measures the number of births occurring at less than 37 weeks of gestation per 100 live births (hereafter labeled as births) during the same time period. Socioeconomic data were drawn from the U.S. Census Bureau s American Community Survey for the years 2007 to We conducted county-level ecological analysis to explore the association between preterm birth rates and three measures of socioeconomic vulnerability: 1) median household income, 2) percent of families living below the federal poverty line, and 3) the GINI coefficient of income inequality. These variables are widely recognized indicators of socioeconomic conditions, and like preterm birth rates, they are inherently aggregate measures of the characteristics of space/place. Individual-level factors associated with individual birth outcomes are immensely important. However, socially relevant aggregates need attention as well, especially in the field of public health where there is concern over incidence rates in the population. 5 Such information may be particularly helpful for targeting service delivery. We constructed a composite variable to measure socioeconomic vulnerability based on each county s combined ranking on the three socioeconomic variables. Higher scores on this socioeconomic vulnerability scale indicate lower incomes, higher levels of poverty, and higher levels of inequality. We recoded our composite variable into four quartiles ranging from low socioeconomic vulnerability to very high socioeconomic vulnerability, and examined the association between our composite measure of socioeconomic vulnerability and county-level preterm birth rates for the overall sample and DeSoto County separately for white and black women. Finally, we reviewed scientific literature concerning the socioeconomic factors that are associated with poor birth outcomes. We gave particular attention to articles published in peerreviewed journals, including the American Journal of Public Health, Journal of Health and Social Behavior, Maternal and Child Health Journal, and Social Science and Medicine. Poverty, Inequality, and Preterm Birth Rates Vary Across Mississippi Counties During the period, the median preterm birth rate in Mississippi counties was just above 17 per 100 live births. At the county-level, preterm birth rates ranged from a low of 10 preterm births per 100 in DeSoto County and a Coahoma County 4 The ACS data originate from a survey conducted with a sample of residents, and all estimates have associated margins of error at the 90% confidence level. 5 Frisbie, W. Parker Infant Mortality. Pp in Handbook of Population, edited by Dudley L. Poston and Michael Micklin. New York: Springer. Page 2

3 high of 30 preterm births per 100 in Coahoma County. Interestingly, these counties are both located in the northwest region of the state the broadly defined Delta and are separated by just one county (Figure 1). We also found disparities in household income, family poverty, and income inequality among Mississippi counties during the period. The median household income across Mississippi s 82 counties during this period was $33,105. However, median household incomes ranged from a low of $20,375 in Jefferson County to a high of $59,734 in DeSoto County. We found a similar gap in the percent of families living below poverty. While the median family poverty rate across counties was 18.8 percent, poverty rates ranged from 7.2 percent in DeSoto County to as much as 38.0 percent in Holmes County. Our measure of income inequality showed less variation among counties, where DeSoto County had the lowest level of income inequality (Gini coefficient = 0.37) and Franklin County had the highest level of income inequality (Gini coefficient = 0.56). 6 Counties with Higher Socioeconomic Vulnerability Have Higher Preterm Birth Rates When we examined the associations between counties preterm birth rates and their median levels of household income, percent of families below poverty, and income inequality, we found significant associations between preterm birth rates and each socioeconomic measure (Table 1). The higher a county s median household income, the lower its preterm birth rate, relative to other counties in the state. Alternately, Table 1. Association between Preterm Birth Rates and Socioeconomic Vulnerability in Mississippi Counties Spearman s rho Association Preterm Birth Rates Median Household Income ** Percent of Families Below Poverty 0.474** GINI Coefficient of Income Inequality 0.251* Socioeconomic Vulnerability Scale 0.452** Sources: Mississippi Department of Health, Vital Records and Statistics; U.S. Census Bureau, American Community Survey. Analysis and table by the University of Mississippi Center for Population Studies. N=82, * p<0.05, ** p<0.01 For a complete list of county preterm birth and socioeconomic vulnerability rankings, see: the higher the percent of families in poverty, the higher the preterm birth rate, compared to other counties. Both of these associations are moderate in strength. Preterm birth rates also are associated with income inequality, but not as strongly as median household income and family poverty. This may be due to the limited variability in inequality between Mississippi counties. The overall socioeconomic vulnerability scale has a moderate association with preterm rates. When we recoded our socioeconomic vulnerability scale into four quartiles, we found a similar relationship between socioeconomic conditions and preterm birth rates. As Figure 2 shows, counties with the highest level of vulnerability also have the highest preterm birth rates. 6 The Gini coefficient ranges in value from 0 (no inequality) to 1 (the highest level of inequality). Page 3

Preterm Births per 100 Births 25 20 15 10 5 0 Figure 2. Preterm Birth Rates by Level of Socioeconomic Vulnerability in Mississippi Counties 2007-2011 15.89 16.53 17.00 16.88 17.00 15.

00 Very High Vulnerability (N=20) Racial Disparities in Preterm Birth Persist at All Levels of Socioeconomic Vulnerability When we explored the relationship between socioeconomic vulnerability and

4 Preterm Births per 100 Births Figure 2. Preterm Birth Rates by Level of Socioeconomic Vulnerability in Mississippi Counties Low Vulnerability (N=20) Moderate Vulnerability (N=21) Average Preterm Birth Rates High Vulnerability (N=21) Median Preterm Birth Rates Very High Vulnerability (N=20) Racial Disparities in Preterm Birth Persist at All Levels of Socioeconomic Vulnerability When we explored the relationship between socioeconomic vulnerability and racial disparities in preterm birth, we found that socioeconomic factors do not fully explain differences in the rate of preterm births between white and black women. Racial disparities in preterm birth rates persist at all levels of socioeconomic vulnerability (Figure 3). Interestingly, average preterm rates for black women are lower in high vulnerability counties than in moderate and low vulnerability counties. Still, preterm rates are highest in very high vulnerability counties. Preterm Births per 100 Births Figure 3. Average Preterm Birth Rates by Race of Mother and Socioeconomic Vulnerability in Mississippi Counties Low Vulnerability (N=20) Moderate Vulnerability (N=21) High Vulnerability (N=21) Very High Vulnerability (N=20) Total Preterm Birth Rates White Preterm Birth Rates Black Preterm Birth Rates Theoretical Perspectives on Preterm Birth, Socioeconomic Conditions, and Race Our analysis of county-level data found that variation in preterm birth rates across Mississippi counties is associated with variations in household income, family poverty, and income inequality. Previous research has demonstrated a persistent link between socioeconomic conditions and individual-level health outcomes. The fundamental causes theory hypothesizes that inequalities in flexible resources (e.g. income, knowledge, and beneficial social connections) are fundamental causes that lead to disparities in a wide range of health outcomes, regardless Page 4

5 of the risk factors associated with a particular outcome. 7 Individuals with higher levels of flexible resources are able to deploy these resources to maintain and improve their health by, for example, earning enough income to live in neighborhoods with health-enhancing amenities. Although individual-level associations are important, research also has demonstrated the existence of neighborhood effects. Across a variety of settings, women who live in areas with high unemployment, low levels of education, a low proportion of high-status occupations, and high poverty levels are significantly more likely to have a preterm birth than those who live in more advantaged settings. 8 Research has also provided support for the cumulative pathways mechanism, which hypothesizes that exposure to stress and disadvantage throughout the life course can negatively influence an individual s current health. A recent study found that women who had lived their entire lives in low-income neighborhoods were significantly more likely to have a child with low birth weight than women who had always lived in high-income areas. 9 In our analysis, measures of socioeconomic vulnerability did not fully explain racial disparities in preterm birth rates between white and black mothers. The weathering hypothesis suggests that racial disparities in birth outcomes over the life course are due to the negative health effects that black women experience as a result of their ongoing exposure to socioeconomic disadvantage, persistent stress, and race-based marginalization. A contemporary study found that African American women (both poor and non-poor) had the highest probability of high allostatic load scores (a measure of cumulative stress) at all ages compared to African American men and White women and men. 10 The concept of intersectional space has been proposed in an attempt to integrate and synthesize research related to racial, socioeconomic, and spatial inequality in birth outcomes. 11 The argument, informed by feminist theory, notes that race, class, gender, and other systems of inequality intersect in the spaces where people live. In subsequent population briefs, we will examine racial disparities in preterm births in more depth, incorporating analyses of maternal age and drawing on the weathering hypothesis and the concept of intersectional space. Conclusion Low levels of household income, high levels of family poverty, and high rates of income inequality are significantly associated with higher preterm birth rates at the county-level in 7 Phelan, Jo C., Bruce G. Link, and Parisa Tehranifar Social Conditions as Fundamental Causes of Health Inequalities: Theory, Evidence, and Policy Implications. Journal of Health & Social Behavior 51(1):S28 S40. 8 Messer, Lynne C., Lisa C. Vinikoor, Barbara A. Laraia, Jay S. Kaufman, Janet Eyster, Claudia Holzman, and Jennifer Culhane Socioeconomic Domains and Associations with Preterm Birth. Social Science and Medicine 67(8): Collins, James W, Jr., Jennifer Wambach, Richard J David, and Kristin M Rankin Women s Lifelong Exposure to Neighborhood Poverty and Low Birth Weight: A Population-Based Study. Maternal and Child Health Journal 13(3): Geronimus, Arline T., Margaret Hicken, Dayna Keene, and John Bound Weathering and Age Patterns of Allostatic Load Scores Among Blacks and Whites in the United States. American Journal of Public Health 96(5). Retrieved ( 11 Green, John J. and Debarashmi Mitra. Forthcoming. Intersections of Development, Poverty, Race, and Space in the Mississippi Delta in the Era of Globalization: Implications for Gender-Based Health Issues. Poverty and Health in America, edited by Kevin Fitzpatrick. Westport, CT: Praeger Publishers. Page 5

6 Mississippi. Related literature suggests that women who lack access to flexible, healthpromoting resources and are exposed to adverse socioeconomic conditions at the neighborhood level are more likely to experience a preterm birth than women who have access to more healthpromoting resources. These findings suggest that local, regional, and statewide efforts to reduce poverty and increase access to beneficial resources, such as high quality education and wellpaying employment, are important to reducing overall levels of preterm births in Mississippi. Furthermore, continued attention is needed on the persistence of racial disparities in preterm births. This issue will be explored further in a future Population Brief. This Population Brief was constructed in collaboration with the Community Foundation of Northwest Mississippi as part of its Right! from the Start Project led by Sannie Snell, with partial support from the W.K. Kellogg Foundation. The views expressed in this report do not necessarily represent these partner organizations. The University of Mississippi Center for Population Studies (CPS) educates, conducts research, and engages in public outreach concerning population issues in the State of Mississippi and beyond. The CPS works in collaboration with the Department of Sociology and Anthropology and numerous partners within the University of Mississippi (UM) system and other institutions, including colleges/universities, nonprofit organizations, and government agencies. Among its programmatic initiatives, the CPS is the lead agency of the State Data Center of Mississippi and the Institute for Community-Based Research. The CPS also houses the Editorial Office of Community Development, the official journal of the Community Development Society. For more information on the Center for Population Studies, please contact: 304 Leavell Hall The University of Mississippi University, MS Tel. (662) Fax (662) Center for Population Studies: State Data Center of Mississippi: Institute for Community-Based Research: Page 6

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