The United States' infant mortality rate fell by 14% from 2005 to 2015, declining from 6.86 to 5.90 deaths per 1,000 live births over the decade, according to data brief released Thursday by the CDC's National Center for Health Statistics (NCHS).

The brief is based on birth and infant death data from the National Vital Statistics System. The data include all infant deaths under age one that were reported on death certificates, as well as all live births that were reported on birth certificates from 2013 through 2015. The brief broke down U.S. infant mortality rates by state, as well as by race and Hispanic origin, but did not examine why disparities exist among regions and racial groups.

Findings

The data showed infant mortality rates continued to vary significantly by state and among races.

Rates by state

The data showed that from 2013 to 2015, average state infant mortality rates ranged from a high of 9.08 deaths per 1,000 live births in Mississippi to a low of 4.28 deaths per 1,000 live births in Massachusetts.

Below is a map showing the average state infant mortality rates in comparison with the country's overall average rate of 5.89:

Rates by race

Broken down by race, the data showed the average national infant mortality rates from 2013 to 2015 among:

• Hispanic women was 4.99 deaths per 1,000 live births;
• Non-Hispanic black women was 11.1 deaths per 1,000 live births; and
• Non-Hispanic white women was 4.95 deaths per 1,000 live births.

Infant mortality rates among those groups also varied by state. According to the data, the average infant mortality rates from 2013 to 2015 among:

• Hispanic women ranged from 3.94 deaths per 1,000 live births in Iowa to 7.28 deaths per 1,000 live births in Michigan;
• Non-Hispanic black women ranged from 8.27 deaths per 1,000 live births in Massachusetts to 14.28 deaths per 1,000 live births in Wisconsin; and
• Non-Hispanic white women ranged from 2.52 deaths per 1,000 live births in Washington, D.C., to 7.04 deaths per 1,000 live births in Arkansas.

The data showed that Alabama, Indiana, and Ohio had infant mortality rates higher than the national rate for each of those three groups, while California, New Jersey, and New York had rates lower than the national rate for each of the three groups.

Reaction

T.J. Mathews, a demographer at NCHS and the data brief's lead author, said the data showed "the lowest [infant mortality] rate for non-Hispanic black [women] is higher than the highest for non-Hispanic white [women] or for Hispanics," which "for people who don't necessarily think about this topic … says a lot."

Paul Jarris—CMO for the March of Dimes, who was not involved in the data brief—said, "We know there are differences in rates of premature birth and maternal mortality and infant mortality based upon social factors, such as educational level, income level, housing safety, safeness of a neighborhood, employment—so factors like this make a big difference," but added, "We have to really take a broader look at what are the social and structural conditions in this country that lead to high rates of infant mortality" and "these unacceptable disparities in infant mortality."

For instance, Jarris noted that a major reason the overall U.S. infant mortality rated declined in recent years is because of the broader use of safe sleep practices, but said, "If a mom lives in a home where she is unable to afford a crib or unable to obtain a crib, and therefore may have to keep the baby in her own bed, that is something that is highly associated with infant mortality."

Alice Chen, an assistant professor of public policy at the University of Southern California who was not involved in the data brief, said previous research has shown that most of the racial gap in infant mortality rates can be explained by lower birth weights and earlier-term births, while the "remaining differences are due mainly … to deaths in the postneonatal period, from one month to one year of life, when infants are out of the hospital system, as opposed to the neonatal period, with survival less than one month" (Howard, CNN, 1/4; Carsen, WBHM, 1/4; Diamond, "Pulse," Politico, 1/4; NCHS data brief, 1/4).

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