— The CDC counters that the methods used in the new study “produce a substantial undercount”
by Rachael Robertson, Enterprise & Investigative Writer, MedPage Today March 15, 2024
A recent study suggesting that the CDC may have overcounted maternal mortality in recent decades is stirring controversy.
Critics, including the American College of Obstetricians and Gynecologists (ACOG) and other experts, say the research could undermine the gravity of maternal mortality and racial disparities.
The descriptive study published in the American Journal of Obstetrics and Gynecology identified maternal deaths through the CDC’s National Vital Statistics System (NVSS), which added a pregnancy checkbox to death certificates in 2003 so that a box would be checked if the deceased person was or had recently been pregnant. Researchers also counted deaths during pregnancy or the postpartum period that specifically mentioned pregnancy among the multiple causes of death on the death certificate.
From 1999 to 2021, maternal deaths increased by 144%, from 9.65 to 12.60 per 100,000 live births, according to NVSS data. But among deaths that explicitly mentioned pregnancy on the death certificate, the rate was much lower and only increased slightly, from 10.2 per 100,000 live births from 1999 to 2002 to 10.4 from 2018 to 2021.
Lead author K.S. Joseph, MD, PhD, of the University of British Columbia in Vancouver, noted that his research group, which included epidemiologists, maternal-fetal medicine specialists, and obstetric medicine specialists, found that “maternal deaths in the U.S. have been overestimated in recent years.”
“In fact, maternal mortality rates have been low and stable, rather than increasing as previously reported,” Joseph told MedPage Today in an email. He also noted that the “results were not entirely surprising as we have been aware of the misclassification of maternal deaths caused by the pregnancy checkbox.”
Joseph and colleagues concluded that “the high and rising rates of maternal mortality in the United States are a consequence of changes in maternal mortality surveillance, with reliance on the pregnancy checkbox leading to an increase in misclassified maternal deaths.”
However, in a statement to Politico Pulse, the CDC said the methods used by Joseph and colleagues “produce a substantial undercount” by missing certain maternal deaths that wouldn’t have been counted unless the pregnancy checkbox hadn’t been checked on the death certificate.
“Capturing these otherwise unrecorded maternal deaths is critical to understanding the scope of maternal mortality in the United States and taking effective public health action to prevent these deaths,” the agency said. “The recent report’s analysis does not address this, nor does it provide evidence of how large any potential overcount may be.”
Veronica Gillispie-Bell, MD, an ob/gyn at Ochsner Medical Center in Kenner, Louisiana, and an expert on maternal mortality and disparities, told MedPage Today that while the controversial study “reveals some of the challenges with identifying maternal mortality by the pregnancy checkbox on the death certificate alone,” it’s only telling one story.
For instance, Maternal Mortality Review Committees (MMRCs) operate on a state or local level and most get funding from the CDC. These committees review and validate maternal death cases, which takes time.
“As we go through that process, we remove cases that have the pregnancy checkbox erroneously checked,” Gillispie-Bell said.
She agreed that NVSS data can be slightly overestimated because the data haven’t been validated yet, which is why the numbers coming from MMRCs are more accurate but take longer to become available. She said this study actually highlights the importance of MMRCs in validating maternal mortality data.
Gillispie-Bell cited a CDC analysis of MMRC from 36 states that showed that mental health disorders were the leading cause of maternal deaths from 2017 to 2019. She pointed out that in Joseph’s study, those deaths would have been missed because “they only included deaths that had a diagnosis that was from a condition caused by pregnancy, missing pregnancy-related deaths.”
“This study has the potential to undermine the work we are doing to garner support to improve maternal outcomes,” Gillispie-Bell cautioned, adding that future work could explore how MMRCs use and validate NVSS data. A federal bill to support MMRCs was introduced last year.
“Those of us who participate in MMRCs know that there are issues with the pregnancy checkbox. That is why our first step is to validate the data,” Gillispie-Bell said. “However, the pregnancy checkbox has been so important as a first step to help us determine when we have a maternal death.”
In a statement from ACOG Christopher Zahn, MD, ACOG’s interim CEO and chief of clinical practice and health equity, noted that the pregnancy checkbox wasn’t added to fabricate a problem but rather to address the real problem of maternal mortality that already exists.
“To reduce the U.S. maternal mortality crisis to an ‘overestimation’ is irresponsible and minimizes the many lives lost and the families that have been deeply affected,” Zahn said.
Joseph thinks the criticism of his team’s study is missing the point.
“Unfortunately, the response from ACOG appears to have been made in haste and we are inclined to dismiss the barrage of inappropriate criticisms as being the product of a rushed process,” Joseph said, adding that they “would be happy to consider and react appropriately to considered and serious criticisms of our study.”
Rachael Robertson is a writer on the MedPage Today enterprise and investigative team, also covering OB/GYN news. Her print, data, and audio stories have appeared in Everyday Health, Gizmodo, the Bronx Times, and multiple podcasts.