ADI and Infant Mortality Link Shed New Light on Maternal Health Crisis

A new study in JAMA Network Open uncovered a link between social vulnerability and NICU morbidity and mortality, adding yet another layer to the maternal health crisis facing the United States.

Particularly, the study showed that a high score on the Area Deprivation Index (ADI) is a risk factor for NICU mortality among extremely premature infants born younger than 29 weeks gestation.

These findings come as the US continues to understand its maternal health crisis. The US has the highest maternal mortality rate of similarly developed nations and the steepest racial disparities in maternal and infant outcomes, previous research has found.

This latest study adds another foil to those figures, noting that greater neighborhood social vulnerability is a risk factor for poor NICU outcomes.

The researchers looked at four NICUs in the Midwest, Northeast, Mid-Atlantic, and South to garner insights about in-hospital morbidity and mortality for extremely premature infants staying in the NICU.

Across the nearly 3,000 infants included in the study, high ADI was linked to in-hospital mortality, the researchers found.

Particularly, ADI was higher among the 498 infants who died before NICU discharge, with the average ADI score being 71. This compares to an average ADI of 64 among infants who did not die prior to NICU discharge.

The researchers also observed a higher median ADI for those with late-onset sepsis or necrotizing enterocolitis (NEC) (68 versus 64) and those with severe intraventricular hemorrhage (IVH) (69 versus 64).

These figures were in line with the researchers’ hypothesis that higher ADI would be linked with worse NICU outcomes, likely because pregnant people from under-resourced neighborhoods may lack the prenatal care access that increases the chances of better birth outcomes.

“The mechanism by which area deprivation affects neonatal outcomes may include the effect of maternal adversity on the developing fetus,” the researchers explained. “Maternal stress and poor access to prenatal care have been linked with adverse birth outcomes. Lower maternal socioeconomic status increases the risk of preterm birth, and among those born prematurely, it increases the risk of adverse neurodevelopmental outcomes.”

These findings also add another layer to the racial health disparities evident in maternal and infant health outcomes. For one thing, Black race was linked to higher ADI; the median ADI among Black infants was 77 compared to 57 for White infants. In other words, Black infants were more likely to have a risk factor for NICU morbidity and mortality. However, Black race itself was not a predictor of NICU morbidity and mortality.

“As racial minority individuals proportionally endure more socioeconomic deprivation, it becomes essential to consider social disparities as a significant mediator of racial disparities,” the researchers offered.

The team added that it is often difficult to parse out the impacts that race and social disadvantage have on health outcomes, largely because the two pair together. That’s likely the result of institutional racism. For example, racist policies like redlining segregated racial minorities into under-resourced neighborhoods, meaning that Black people and other racial/ethnic minorities are more likely to live in places with higher ADI scores.

Generally, these findings provide an explanation for a phenomenon scientists already knew existed; Black babies have worse infant mortality rates than White babies. Per CDC figures, non-Hispanic Black babies face and infant mortality rate that is more than double that of non-Hispanic White babies, coming at 10.6 deaths per 100,000 live births and 4.5 deaths per 100,000 live births, respectively. For Hispanic babies, the infant mortality rate was 5 deaths per 100,000 live births.

Future public health investigation is necessary to determine how to mediate these barriers, the JAMA researchers indicated.