Maternal mortality in the US more than doubled between 1999 and 2019, according to new research, but not all racial and ethnic groups were equally impacted. The largest increase was seen among the American Indian/Alaska Native (AI/AN) population and the highest rates of maternal mortality persist among Black women.1
The observational study from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington and Mass General Brigham is the first analysis of its kind to include all US states and to examine differences in maternal deaths in each state by 5 specific racial and ethnic groups. In several states where AI/AN and Black women were found particularly at risk, these inequities have not been previously reported, according to study authors.
During the 10-year period studied, the median state maternal mortality ratio (MMR), ie, maternal deaths per 100 000 live births, increased from 14.0 to 49.2 among the AI/AN population, and from 26.7 to 55.4 among the Black population. The measure for the Black population remains the highest in the US, the investigator report in JAMA.
"Maternal mortality is a crisis in the United States. These rates have been increasing over the past several decades and were exacerbated by the pandemic," said co-first author Allison Bryant, MD, MPH, senior medical director for health equity at Mass General Brigham, in a news release.2 "Our study sheds light on the wide disparities within maternal mortality rates — the specter of maternal death differentially burdens some ethnic and racial populations."2
Bryant and colleagues note further, that "Maternal mortality persists as a source of worsening disparities in many US states and prevention efforts during this study period appear to have had a limited impact in addressing this health crisis."1
Median state MMRs increased also for the other 3 racial/ethnic groups examined in the study: Asian, Native Hawaiian, or other Pacific Islander: 9.6 to 20.9; Hispanic: 9.6 to 19.1; and White: 9.4 to 26.3.
The investigators observed that both MMR and racial/ethnic disparities varied widely across the country. Maternal mortality in the South was high across all racial and ethnic groups, and particularly high for Black women. The highest MMR in some states in the Northeast was also for Black women and those rates tripled over the time of the study, they reported. The highest rates of MMR were found for AI/AN women in the Midwest and the Great Plains states.
In Oregon, Hawaii, Colorado, Illinois, Wisconsin, Delaware, Vermont, and Rhode Island, 2019 MMR values were lower for all racial and ethnic groups, a finding the authors suggest may be the result of lower prevalence in these states of risk factors that drive maternal deaths or the success of some prevention efforts in these locations.
"Often, states in the South are called out as having the worst maternal mortality rates in the nation, whereas California and Massachusetts have the best. But that doesn't tell the whole story," Bryant said. "It's essential to look at the disparities between populations that exist even in the 'best' states." Previous research of maternal mortality has looked at groups of states or at the country as a whole but not at individual states on a comparative basis.
The research team used the National Vital Statistics System data on deaths and live births in each state and racial/ethnic group between 1999 and 2019, compiling data on pregnant or recently pregnant individuals aged 10 to 54 years. They used a Bayesian extension of the generalized linear modeling framework models for births and deaths separately in each state and racial and ethnic group.
Bryant et al reported 1210 maternal deaths in 2019, a 2-fold increase from 505 deaths recorded in 1999.
Among the study’s limitations, the team cautioned that racial and ethnic data is vulnerable to misclassification and, although at the national level this type of error tends to be small, there may be some residual effects in their analysis. They also note that the addition by states of a pregnancy checkbox on death certificates has been ongoing for the past 20 years, which they say complicates comparisons across states.
Describing disparities in maternal mortality as “just the tip of the iceberg,” Greg Roth, MD, MPH, associate professor in the division of cardiology and director of the program in cardiovascular health metrics at IHME, says they are a good reflection of the health risks faced in the states where the deaths are most common. Vascular disease such as severe hypertension or blood clots often lead to maternal deaths, drivers similar to those for myocardial infarction, stroke, and heart failure. The IHME research, he says, can help focus policy and prevention efforts on the states—and the population groups—that need it most.