Medicaid expansion was associated with statistically significant declines in mortality rates among Black infants in 2018 to 2019 and Hispanic infants in 2015 to 2019, according to researchers.

“Increasing insurance coverage take-up among eligible populations continues to be an instrumental yet not fully realized lever for insurance expansions to further benefit population health, particularly by reducing Infant Mortality Rate (IMR) in this case,” Joanne Constantin, MPH, a PhD candidate at the University of Iowa, and colleagues wrote in the American Journal of Preventive Medicine.

To examine year-by-year effects of the 2014 Affordable Care Act Medicaid expansion, the researchers used a difference-in-differences event-study design to analyze publicly available 2011 to 2019 Multiple Cause of Death data. They then compared infant mortality changes in the states that expanded in 2014 with states that did not.

The researchers found that Medicaid expansions were linked to a significant decline in Black infants’ mortality, dropping by 1.19 per 1,000 live births (95% CI, 2.27 to 0.12) in 2018 and 1.35 deaths per 1,000 live births (95% CI, 2.45 to 0.26) in 2019.

“Considering that Black infants’ IMR is currently more than double that among white infants, this finding is especially important from a policy and prevention perspective,” Constantin and colleagues wrote. “It suggests a potential for long-term effects of expanding health insurance to low-income women of childbearing age in pre-pregnancy phase (not only during pregnancy), translated through reduced infant mortality among the group experiencing the highest IMR.”

Hispanic infants also saw a decline in mortality in 2015 to 2019, including by 0.8 per 1,000 live births (95% CI, 1.25 to 0.36) in 2015 and 1.28 per 1,000 live births (95% CI, 1.88 to 0.68) in 2019.

“The finding of a sustained decline in Hispanic infants’ IMR is also novel and important; despite lower IMR in this group, it appears to relate to pathways affected by Medicaid expansions including a larger proportion of mothers gaining coverage preconception,” the researchers wrote.

Constantin and colleagues found that in 2019, overall infant mortality dropped by 0.37 deaths per 1,000 live births (95% CI, 0.70 to 0.05).

The researchers concluded that “the study adds evidence on the association of the Affordable Care Act Medicaid expansions with a decline in mortality of Black and Hispanic infants” and that “the findings shed light on the importance of examining year-by-year effects over multiple years.”

“Further research examining conceptually relevant mechanisms including preconception care and maternal health, coverage and health services use during postpartum, and use of family planning services would also be fruitful,” they wrote. “A more granular understanding of contributors to Medicaid take-up before, during and after pregnancy and how Medicaid expansions modified enrollment decisions is needed.”