Are rising US maternal mortality rates inflated?

March 15, 2024 - A new study published in the American Journal of Obstetrics & Gynecology is calling into question the high US maternal mortality rate, stating that many of the maternal deaths documented in the United States are not due to pregnancy or childbirth.

Update 2024/03/15: This article has been updated with a public statement from the American College of Obstetrics and Gynecology.

Rather, a lax documentation practice meant many deaths among pregnant people that were unrelated to pregnancy or childbirth were regarded as maternal deaths.

These findings come as the healthcare and public health industries have zeroed in keenly on the rising rate of maternal and infant death in the US.

In July 2023, researchers wrote in JAMA that the maternal mortality rate in the US more than doubled between 1999 and 2019, from a total of 505 maternal deaths to 1,210. According to The Commonwealth Fund, the US has the worst maternal mortality rate in the developed world, and that’s complemented by the worst maternal health disparities in the developed world.

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This latest study turns those figures on their head.

Using National Center for Health Statistics data from between 1999 and 2021, the researchers looked at deaths that required a mention of pregnancy among the causes of death on a death certificate.

The assessment reflected what the JAMA article found: maternal deaths increased by 144 percent during the study period. But further analysis showed that the rise in maternal deaths wasn’t due to direct obstetrical death, meaning a death tied to pregnancy or childbirth. Direct obstetrical deaths increased from 8.41 per 100,000 live births in 1999-2002 to 14.1 in 2018-2021.

Rather, the increase was tied to indirect obstetrical death, meaning death not caused by pregnancy or childbirth but which happened while pregnant or was exacerbated by pregnancy. Indirect obstetrical deaths rose much more starkly, from 1.24 per 100,000 live births in 1999-2002 to 9.41 in 2018-2021.

The researchers did not argue that maternal mortality is not a problem in the US, but they did indicate that the numbers could be overinflated due to how the industry fills out death certificates for pregnant women.

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“Several of our findings suggest that the pregnancy checkbox is responsible for a substantial misclassification of nonmaternal and incidental deaths (as maternal deaths), and a consequent overestimation of maternal mortality,” the team wrote.

Overall, 87 percent of indirect obstetrical deaths were identified via the positive pregnancy checkbox on the death certificate. For direct obstetrical deaths, that figure was 38 percent.

Said otherwise, the positive pregnancy checkbox may cause public health experts to flag maternal deaths that were not, in fact, caused by pregnancy or childbirth. Indeed, a breakdown of the data shows that direct obstetrical deaths from factors like preeclampsia or postpartum hemorrhage remained somewhat stable during the study period.

“Although the reason for such pregnancy checkbox errors is unclear, possible causes could include misunderstanding regarding the utility and importance of death certificate information on the part of the certifying physician, competing priorities on physician time, or inexperience,” the researchers said.

“One potential solution for improving pregnancy checkbox-aided maternal death identification would be to require certifying physicians who tick the checkbox to specify the pregnancy-related cause of death,” they added.

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None of this is to say that maternal mortality does not warrant public health attention in the US, the researchers stressed. However, by more specifically clarifying cause of death, public health experts may be able to tailor screening initiatives.

“Identifying maternal deaths by requiring the mention of pregnancy among the multiple causes of death provides a more accurate, clinically coherent and compelling perspective on maternal mortality in the United States, and can serve as the evidentiary basis for clinical and public health initiatives,” the researchers concluded.

Healthcare industry leaders that focus on maternal health are reasserting the maternal health crisis across the nation. In a statement issued a day after the study ran, the American College of Obstetricians and Gynecologists (ACOG) stressed that maternal mortality is at a crisis point.

“Using their methodology, the authors found that there had been decreases in maternal deaths rates for some conditions, such as hypertension, hemorrhage, and preeclampsia," reads a public statement attributed to Christopher M. Zahn, MD, FACOG, interim CEO and chief of clinical practice and health equity and quality of ACOG. "This shows that nationwide and regional programs to eliminate deaths from preventable pregnancy-related conditions, such as the Alliance for Innovation on Maternal Health, are working. But where we still fall short is in successfully addressing significant, existing racial health disparities, which were mentioned only briefly in this manuscript. Additionally, the authors pointed out that mortality rates had increased for several conditions, including placenta accreta syndrome, cardiomyopathy, and preexisting hypertension. So there is still a lot of work to do."

“The authors have created discrete categories to discredit the pregnancy checkbox, which, while somewhat flawed in its implementation, was not created to fabricate a problem," the statement continued. "It was created to address an existing one. It is one of multiple sources of data we have—each with its own pros and cons, showing different aspects of maternal health outcomes—that help to provide information so that we can create actionable solutions."