Rural-Urban Disparities in Mortality Among US-Born Preterm Infants.

Background: US infant mortality rate (IMR), defined as deaths under 1 year of age per 1000 live births, is higher among rural infants than their urban counterparts. Although much is known about rural-urban inequities in IMR, disaggregated data by preterm birth status are lacking.

Objectives: (1) Evaluate the differences in rural-urban IMR among preterm infants born earlier than 37 weeks' gestation. (2) Determine the prevalence and predictors of infant mortality by race and ethnicity and rural or urban residence.

Methods: Linked national birth and death certificate data from 2005 to 2014 were used. Rural and urban residence was categorized based on 2013 Urban Influence Codes. χ2 analysis was used to compare sociodemographic and clinical characteristics by residence. Multivariable logistic regression was used to assess the independent association between preterm IMR, residence, race, and ethnicity.

Results: Among 4 095 410 preterm births, 132 388 (3.23%) infants died. Rural preterm infants experienced higher odds of infant mortality (adjusted odds ratio [aOR], 1.09; 95% CI, 1.07-1.11) compared with their urban counterparts. Compared with preterm infants born to urban non-Hispanic white individuals, those born to rural non-Hispanic white (aOR, 1.10; 95% CI, 1.07-1.12) and American Indian and Alaska Native (aOR, 1.33; 95% CI, 1.22-1.46) individuals had higher odds of infant mortality.

Conclusion: Overall, preterm infants residing in rural counties are more likely to experience infant mortality compared with their urban counterparts with differences noted by race and ethnicity. These data support the need to develop interventions to mitigate mortality in the rural preterm population throughout the first year of life.