Background Undocumented immigrants constitute a highly vulnerable population that may experience increased risk of negative health outcomes for newborn children. The spatial relationship between the proportion of undocumented immigrants residing in an area and negative birth outcomes has not been studied on a national scale, although real and perceived access to healthcare are unlikely to be geographically consistent.
Methods We compiled estimates of the percent of undocumented immigrants, negative newborn health outcomes, and socioeconomic data for 173 counties in the United States, drawn and calculated from publicly-available databases. We used a negative binomial regression model to determine the relationship between undocumented immigrants and three negative birth outcomes: NICU admission, low birth weight, and infant mortality. Incidence rate ratios are reported as the primary analytical metric.
Results A higher proportion of undocumented immigrants in a county was not a significant predictor of higher rates of negative health outcomes for newborns. However, counties with a higher Hispanic/Latino population, higher African American population, and higher percentages of persons with bachelor’s degrees were all associated with poorer outcomes. NICU admission rates were higher in counties with a high Hispanic/Latino population (IRR: 1.31) and counties with a high African American population (IRR: 1.29). Low birth weight had a similar trend (High Hispanic/Latino population IRR: 1.39; High African American population IRR: 1.32), along with infant mortality (High Hispanic/Latino population IRR: 1.37; High African American population IRR: 1.30). Those with high proportions of Republican voters were less likely to have negative birth outcomes; the incidence rate ratio for negative birth outcomes among a high level of Republican voters was 0.74 for admission into the NICU and 0.72 for low birth weight.
Conclusion We did not find a statistical association between counties with high rates of undocumented immigrants and negative health outcomes for newborns. This could be the result of the healthy immigrant effect, incomplete data on undocumented immigrants, or there may be an association not statistically detectable at such a large spatial scale.