Infant mortality in the Lower Mississippi Delta: geography, poverty and race

The objectives of this study were to explore regional, economic and racial disparities in infant mortality rates between geographic sub-regions within the eight states containing the Delta and to test hypotheses that regional disparities would decrease over time while county poverty level and racial composition would remain significant predictors of infant mortality rates.

The study used secondary data analysis of county level rates, including descriptive statistics, hierarchical multiple regression with interaction effects and linear multiple regression. Models testing the impact of sub-regional geographic differences, percent of poverty, percent of black population and interaction effects were conducted at three time periods, the late 1970s, late 1980s and late 1990s.

In the first time period, regional differences, percent of poverty, percent of black population and the interaction of region and poverty were all predictive of infant mortality (R(2) = 0.31, P < 0.0001). In the subsequent time periods, only percent of poverty and percent of black population were significant predictors (R(2) = 0.20, P < 0.0001 and R(2) = 0.26, P < 0.0001).

During the late 1970s and early 1980s, region, poverty and racial composition of counties all played an important part in predicting life chances for infants born in these eight states. Furthermore, Central Delta infants in counties with poverty levels of 30% or greater were significantly more likely to die than infants in other areas with the same rates of poverty, even after controlling for racial composition. The impact of regional differences was no longer significant at the ends of the subsequent two decades. Both medical and policy changes during these decades may have contributed to the decreased impact of region. However, both poverty and racial composition continue as important factors, accounting for more variance in the late 1990s than a decade before.