After decades of improvement, health inequality between infants in the U.S. is widening, according to a recent study.

Published in December in SSM-Population Health, the study found that infant health inequality has grown steadily since 2010. The increase happened as income inequality also worsened in the nation, suggesting a possible link between the two factors.

For the study, researchers at Brown University analyzed data from the National Vitality Statistics System, a registry that records key infant health statistics. The system collected data on almost 22 million births, tracking maternal health risk factors such as education level, marital status and employment.

In the past decade, the researchers found the health gap between infants born to the most socially advantaged mothers and mothers at the other end of the spectrum steadily increased. The sharpest increase in infant health inequality was found between mothers who did not finish high school and mothers who had graduated from college. And while health risks improved for infants born to married mothers, they worsened for infants born to unmarried mothers.

Emily Rauscher, PhD, Mphil, MS, study co-author and an assistant professor of sociology at Brown University, said she was surprised by the widening health inequalities. When the Affordable Care Act was implemented in 2010, one of its goals was to reduce health disparities.

"Even though the ACA increased access to care, it did not increase access to quality care," Rauscher told The Nation's Health.

The biggest disparity in infant health outcomes was found when white, married, college-educated mothers were compared to mothers who were Black, unmarried and lacked a high school degree. In the first group, low birthweight among infants decreased by about 0.1% after 2010, while for the second group, it increased at a rate of about 1.5% per decade, the study said.

The researchers suggested systemic changes, such as work to prevent high school dropout and implement a universal basic income, which could improve the health of pregnant women. To help ensure equal health care, Rauscher also proposed a checklist for doctors to use with pregnant women, double-checking that goals are met for every patient.

The stakes are high, as poor maternal health can have a lasting effect on children's health.

“Inequalities that start in early childhood manifest over time and can lead to bigger inequalities,” David Rangel, PhD, MS, co-author of the study and an associate professor of education at Brown University, told The Nation's Health. “Kids that start with lower birthweight are likely to have health consequences from it later in life.”

Since 2010, low birth weight for Black American infants has increased, a new study says. (Photo by 1BrightStar, courtesy iStockphoto)