Parental income and race appear to play a significant role in infant mortality.
That’s the conclusion of a research paper circulated this week by the National Bureau of Economic Research, a Cambridge, Mass.-based nonprofit. The study, titled “Maternal and Infant Health Inequality,” crunched data from California birth records from 2007 to 2016.
The researchers gleaned data from the California Department of Health Care Access and Information, a department within the California Health and Human Services Agency, and from Internal Revenue Service tax records.
Infants born into low-income families experience higher mortality rates in their first year of life compared to those born into the highest-income households, the paper found. Maternal mortality rates are also the greatest among mothers who have the lowest income.
Infant and maternal health were best for non-Hispanic white families and worst for non-Hispanic Black families. The gaps between the two groups are larger than the income differences within a race.
“‘Infant and maternal health in Black families at the top of the income distribution is markedly worse than that of white families at the bottom of the income distribution.’”
— ‘Maternal and Infant Health Inequality’ report
“Indeed, infant and maternal health in Black families at the top of the income distribution is markedly worse than that of white families at the bottom of the income distribution,” the researchers wrote.
That means even the highest-income Black mothers and their newborns actually experience worse infant and maternal mortality rates than their lowest-income white counterparts.
The findings point to deep-seated racial biases in the U.S. healthcare system and other areas, Maya Rossin-Slater, one of the co-authors of the paper and an associate professor of health policy at Stanford University, said in a statement.
“We hear stories like Serena Williams’ and tend to think of them as exceptional, but our data suggest that’s not true,” she added, referring to the tennis star’s account in a 2018 Vogue story that she experienced complications after giving birth, and struggled to get medical staff to listen to her concerns.
Black women are three times more likely to die from a pregnancy-related cause than their white counterparts, according to the Centers for Disease Control and Prevention.
But the quality of healthcare is not the only factor explaining these inequities, Rossin-Slater noted. Resources like paid family leave, access to which is highly inequitable across different socio-economic groups, also impact the well-being of both the mother and newborn, she said.
“The stark inequities by income and race in California are particularly striking given that the state has one of the most generous social safety-net systems in the U.S., and is also well-known for its efforts to improve maternal and infant-health outcomes and address racial disparities,” added the paper’s authors, who came from Stanford University, New York University, Columbia University, the University of Michigan and the U.S. Census Bureau.
The U.S. has a higher infant mortality rate and maternal mortality rate than other wealthy countries. In fact, the U.S. infant mortality rate ranked 33rd out of the 38 countries included in the Organization for Economic Cooperation and Development’s infant mortality report for 2021. For every 1,000 live births, there were 5.4 deaths in the U.S. in 2021.
And yet the U.S. ranked first in the world in terms of scientific advancement within healthcare, according to the World Index of Healthcare Innovation in 2020. The U.S. ranked fourth, behind Switzerland, Germany and the Netherlands. It fared high in categories such as quality, choice, and science and technology, but scored low in fiscal sustainability, ahead only of Japan.
The researchers also found that lower-income mothers were more likely to have infants with normal weight compared to mothers in the highest income level. (Low birth weight can indicate serious health problems.) Mothers in the highest income tier were also older, and sometimes more likely to have non-singleton births, meaning they gave birth to more than one child.
Non-singleton births — twins or triplets, for example — usually have lower body weights and are substantially more likely to occur in pregnancies assisted by fertility treatments, the authors noted. Studies show people who use fertility treatments are disproportionately older and wealthier, given the high costs.
While children born into top-income-level households had worse birth outcomes than those born into the bottom of the income distribution, they still had lower mortality rates.