An Ecologic Analysis of Preterm Births in Appalachian Counties of Tennessee by Economic Level

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Background: Preterm birth (PTM) (< 37 weeks gestation) has been associated with low economic status characteristics like rural residence, county with low average per capita income, poverty, and unemployment. Infants born PTM are at greater risk of health and developmental problems and mortality. The primary objective of this study was to explore the trends in the association between PTM and economic level for Appalachian counties in Tennessee. The results from this study will support hypothesis development for future study on PTM in this region. Methods: PTM data from year 2009 to 2013 for each county in Tennessee was used for the analysis of trend. Proportion of PTM live births for each county and each year was computed to estimate prevalence. Appalachian Regional Commission (ARC) uses an indexbased county economic classification system applying three economic indicators – three-year average unemployment rate, per capita market income, and poverty rate – to classify each county into one of the five categories, namely, Attainment, Competitive, Transitional, At-Risk, and Distressed, that is ranked from best off to worst off respectively. Using this classification by the ARC, Appalachian counties were stratified by economic level to explore the association with PTM prevalence. Results: Forty-three out of 95 counties in Tennessee are defined by ARC as Appalachian. When classified by economic level, none of the counties in the Appalachian region fell into the highest (Attainment) sub-category of economic level for any of the five years observed, and for years 2011 to 2013 none of the counties fell into the second highest sub-category (Competitive) of economic level. Moreover, just one county was categorized as Attainment in year 2009, and just two for the year 2010. Not much difference was observed in PTM prevalence for sub-categories of economic level of Appalachian counties over the five-year period (2013 Distressed 11.67%, At risk 11.47%, Transitional 11.64%; 2012 Distressed 11.51%, At risk 12.10%, Transitional 11.58%; 2011 Distressed 10.04%, At risk 11.52%, Transitional 11.50%; 2010 Distressed 12.03%, At risk 11.42%, Transitional 11.83%, Competitive 11.40%; 2009 Distressed 10.68%, At risk 11.75%, Transitional 11.04%, Competitive 10.85%). Regardless of the inconsistent pattern of PTM prevalence observed for both Appalachian and non-Appalachian counties, the average prevalence for Appalachian counties (2009 11.19%, 2010 11.73%, 2011 11.26%, 2012 11.75%, 2013 11.59%) has been higher than non-Appalachian counties (2009 10.77%, 2010 10.32%, 2011 10.35%, 2012 10.90%, 2013 10.70%) for all years observed. Interestingly, the national prevalence of PTM is declining while prevalence in Tennessee (2009 11.00%, 2010 11.09%, 2011 10.84%, 2012 11.36%, 2013 11.19%) has remained essentially unchanged. Conclusion: PTM prevalence is higher in Appalachian counties of Tennessee compared to nonAppalachian counties. No meaningful change in PTM prevalence was observed by categories of economic level. However, it is likely that analysis based on the aggregate data could have masked the true differences in PTM birth by economic status. Therefore, individual data on PTM and economic status would be necessary to make any inference on the association.

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