Skip to content

For years, birth workers and maternal advocates in the US have been horrified by the rates of maternal mortality reported yearly. How could the best funded healthcare system in the world be failing mothers so badly?

New research by Rutgers Health and other universities suggests that it may not be. In fact, they believe the numbers have been catastrophically miscalculated due to flawed surveillance techniques.

According to the National Vital Statistics System (NVSS) of the Centers for Disease Control and Prevention (CDC), maternal death rates have tripled over the last twenty years. In 2021, the reported rate reached 32.9 deaths per 100,000 live births, significantly higher than in any other developed country. 

But, according to this new study published on March 12 in the American Journal of Obstetrics & Gynecology, maternal mortality rates in the United States have remained constant and are comparable to those in other developed nations.

Maternal deaths refer to deaths that occur during pregnancy, childbirth, or shortly after due to conditions that are directly related to or worsened by pregnancy or birth. Deaths caused by accidents or unrelated to the deceased’s pregnancy or recent delivery should not be included in the maternal death rate. Unfortunately, the researchers believe a critical flaw in the reporting methodology of the National Vital Statistics System (NVSS) often results in those unrelated deaths being added in.

Cande Ananth, the Chief of the Division of Epidemiology and Biostatistics in the Department of Obstetrics, Gynecology, and Reproductive Sciences at Rutgers Robert Wood Johnson Medical School, is the study’s senior author. According to Ananth, “The CDC has acknowledged in the past that errors were artificially inflating numbers, but their efforts to correct those errors haven’t worked.” 

“On the contrary, official estimates show maternal death rates nearly doubling between 2018 and 2021, which clearly hasn’t happened. Still, many media outlets have reported these figures as correct, and it’s important to set the record straight,” Ananth added. “Accurate numbers are important to know where we stand and how we need to allocate money and effort to make improvements going forward.”

The study finds that improvements in obstetrical care have actually decreased death rates, but deteriorations in patient’s general health have offset those gains, resulting in keeping the overall death rate stable.

So what’s the flaw?

In 2003, the inclusion of a simple pregnancy checkbox on U.S. death certificates led to an increase in maternal death rate estimates. An errant checkmark was all that was necessary to cause a death to be included. Even when the deceased woman was over 85 years old or biologically male, if the death certificate with had a positive pregnancy checkbox, it was added to maternal rates. It was these errors resulted in the CDC discontinuing the reporting of maternal death rates entirely between 2007 and 2017.

As of 2018, the NVSS restricts the use of checkbox information to women aged between 15 and 44. However, the NVSS still categorizes a significant number of non-maternal and incidental deaths as maternal deaths.

“If you’re pregnant and die in a car crash, that’s not a maternal death,” Ananth said. “A big change driving recent increases in the official numbers stems from the tendency to include more and more cancers unrelated to pregnancy in maternal death rates. A woman who had a diagnosis of breast cancer before conception and then died after the pregnancy ended or – a woman who would have died if she’d never gotten pregnant – will be counted as a maternal death.”

The study’s authors calculated maternal death rates for two distinct periods: 1999 to 2002 and 2018 to 2021. They used two approaches to arrive at these rates. Firstly, they employed the methodology stated by the National Vital Statistics System (NVSS) and obtained figures that almost matched the officially published rates. Secondly, they limited maternal deaths to those cases where pregnancy was listed as a cause of death at least once on the death certificate.

According to the CDC method, the maternal death rate was 9.65 per 100,000 live births during the 1999-2002 period and increased to 23.6 during the 2018-2021 period. However, the alternative method calculated the death rates at 10.2 and 10.4 per 100,000 live births, respectively. These statistics radically contradict the previously held belief that maternal death rates in the United States have been increasing. Fortunately, as stated by Ananth, this does not seem to be the case.

Researchers found that healthcare during pregnancy and after delivery has improved in many areas. There was a significant reduction in maternal deaths caused by infections, hypertensive disorders, and other treatable causes. Although there was a slight narrowing of differences in death rates by race, significant differences remain, with Black women having the highest death rate and Hispanic women the lowest.

“Our study, which identified maternal deaths using a pragmatic definition-based methodology, showed stable rates of maternal mortality and a reduction in deaths from obstetrical complications,” said K. S. Joseph, lead author of the new study and a professor of obstetrics and gynecology at the University of British Columbia, Canada. “Moreover, the analysis by cause-of-death provides evidence that can enable focused prevention initiatives targeted at high-risk and vulnerable subpopulations.”

This is fantastic news. If our goal is zero deaths as a result of pregnancy complications, we cannot make accurate decisions about how to change care without accurate information. We’re excited to see further improvements in care as a result of this better data.