Maternal Morbidity and Mortality:

Are they really up? And what’s the role of measurement changes, real-world factors, and racism?

By Kelly Harrington and Luc Schuster

June 27, 2024

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U.S. maternal deaths keep rising.” “Maternal deaths in the U.S. more than doubled over two decades.” Startling headlines like these warn of a growing maternal health crisis in the United States. Indeed, the data show a steady doubling of the maternal mortality rate over much of the 2000s, leading into an even larger spike during the COVID-19 pandemic.

It turns out, though, that basically all of this reported increase in maternal mortality up to 2017 is the result of new data measurement and reporting practices that were gradually adopted by states over the time period of this increase, not an actual rise in mortality. While maternal mortality does appear to have momentarily increased during the early years of the COVID-19 pandemic, there actually is little evidence of an alarming rise in maternal mortality, as suggested by some of the news coverage. We discuss this in more detail later. It's important to note that these measurement improvements were made to correct for the systematic undercounting of maternal deaths. Although maternal deaths likely didn't increase significantly in the 2010s, we now know that maternal mortality rates are higher than previously thought. In Massachusetts, we’ve also seen reported rates of serious complications in pregnancy and childbirth, known in public health circles as maternal morbidity, increase in recent years. The Massachusetts severe maternal morbidity rate—the rate of labor and delivery complications that result in significant short-or long-term health consequences—nearly doubled between 2011 and 2020, jumping from 52.3 to 100.4 per 10,000i  deliveries.

As with reports of increases in maternal mortality, it’s likely that some portion of the increase in SMM is attributable to measurement changes and possibly to an increasing awareness among health-care providers of conditions that make up SMM, leading to increased identification and reporting of associated conditions. However, it appears that measurement changes don’t explain the full increase in SMM, unlike with maternal morbidity.

In this brief, we’ll dig into the measurement changes driving higher levels of reported maternal deaths, as well as the role that COVID-19 played. We explore the likely real-world factors driving some of the reported increases in severe maternal morbidity. And we investigate why racial disparities are so large, regardless of measurement approach. We expect there are other contributing factors behind each of these, but we’ve done our best to summarize what we’ve found in the data and other research.

What are maternal morbidity and mortality and why do they matter?

Mortality and morbidity sound similar but have different meanings. Maternal mortality refers to pregnancies that result in the death of the mother. Severe maternal morbidity (SMM) refers to unexpected health issues during childbirth that harm a woman’s health, including life-threatening conditions like cardiac arrest, eclampsia, and pregnancy-related sickle cell disease complications.

Although less extreme than death, SMM is also important to understand because it includes life-threatening conditions that can pose significant long-term health risks beyond the postpartum period. SMM is also more commonplace. For every maternal death, there are about 100 instances of SMM. Most pregnancies and deliveries are uncomplicated, but SMM still affects 50,000 women nationwide and 400 women in Massachusetts every year, according to the Massachusetts Department of Public Health. Furthermore, Black women experience significantly higher rates of SMM and death, highlighting substantial racial disparities that warrant attention and action. We’ll dive deeper into these disparities later in the brief.

Also troubling is the fact that U.S. maternal morbidity and mortality rates appear to be higher than in other high-income countries, such as the UK, Japan, and Germanyii. In 2022, the maternal mortality rate in the U.S. was 22.3 deaths per 100,000 deliveries, more than double that of other high-income countries. Especially disturbing is the markedly elevated mortality rate for Black mothers. While Massachusetts has a lower rate than the U.S. overall, it’s still higher than other high-income countries. This disparity is partly due to policy differences, such as universal healthcare in those comparison countries, while many Americans remain uninsured. Additionally, other countries offer more generous paid maternity leave and more comprehensive postpartum support.

Massachusetts fares better than other states.

In Massachusetts, 15.3 per 100,000 deliveries resulted in a maternal death between 2018 to 2021, putting Massachusetts among the states with the fewest maternal deaths. This is likely due to the quality and comprehensiveness of care available to mothers in Massachusetts. The Commonwealth Fund ranks Massachusetts first for reproductive care and women’s health. The four states with fewer maternal deaths are Colorado, Minnesota, Wisconsin, and California, all states with more comprehensive maternity care services and better maternal health outcomes than other U.S. states.

Conversely, Massachusetts has one of the highest rates of severe maternal morbidity, ranking 45th of all states according to the Commonwealth Fund. Interestingly, other states with low maternal mortality rates and higher-quality maternal health care—like California, Colorado, and Minnesota—also rank poorly for severe maternal morbidityiii. This may be due to stronger health-care systems in these states that are more likely to catch and reliably code SMM complications. By identifying and treating these complications early, they prevent deaths, resulting in low maternal mortality rates despite high SMM rates.

Racial disparities are large, especially for Black women.

As with maternal mortality, it is disturbing that Black women consistently have the highest rates of severe maternal morbidity (SMM), and the gaps between them and women of other races have increased in recent years. In Massachusetts in 2020, the SMM rate was 190.8 per 10,000 deliveries among Black women, 114.7 per 10,000 among Asian and Pacific Islander women, 111.9 among Latina women, and 78 among White women. Rates of SMM among Native women are too small to report for 2020 alone, but we know that between 2011 and 2020, Native women in Massachusetts experienced SMM at a rate of 78.4 per 10,000 deliveries. In 2020, Black women experienced SMM at 2.3 times the rate of White women, a disparity that increased by 25 percent between 2011 and 2020.

As we saw in an earlier graph, Black women also experience maternal mortality at much higher rates. In 2022, the U.S. maternal mortality rate among Black women was at least double the rates of Asian, Latina, and White women. Among Black women, the maternal mortality rate was 49.5 deaths per 100,000 deliveries, compared to 19 deaths among White women, 16.9 among Latina women, and 13.2 deaths among Asian women. These high 2022 rates are actually a decrease from 2021. Between 2021 and 2022, for instance, the maternal mortality rate for Black women decreased by 29 percent from a staggering 69.9 deaths per 100,000 deliveries in 2021.

Unfortunately, we can only present maternal mortality by race at the national level due to small sample sizes and data availability, but given what we know about failure to recognize Black women’s health concerns in mainstream medical settings, it’s not unreasonable to believe the trend of racial disparity holds true in every state, including Massachusetts.

Are maternal morbidity and mortality really up?

As noted above, despite all the attention paid to the worrisome increase in reported maternal mortality rates, it turns out that nearly all of the increase up to 2017 was driven by measurement changes.

Prior to 2003, death certificates didn’t include enough information to accurately track maternal deaths, resulting in an undercount. To correct this, the Centers for Disease Control (CDC) recommended adding a checkbox on state death certificates that health-care providers check when the person who died is pregnant or has been pregnant recently. The state-level implementation of the checkbox was staggered between 2003 and 2017, meaning states implemented the change any time during that 14-year timeframe. This staggered implementation made data reporting during this timeframe inconsistent and 2017 was the first year that maternal mortality was reported with all states having implemented the checkbox—explaining why, as highlighted in the first graph in this brief, we see a major increase in maternal mortality in 2017. The increase looks startling, but it’s almost entirely an artifact of measurement changes.

The addition of the checkbox on state death certificates allowed for more accurate identification of maternal deaths overall, though evaluations found that it led to some with misclassifications of some deaths, especially among the 45+ age group. This is partially because it incorrectly classified some deaths of nonpregnant women as maternal deaths and because the coding practice at the time was to count any death as pregnancy-related if the checkbox was checked, regardless of whether there was other evidence that the death was primarily related to pregnancy—and, unfortunately, the likelihood of death increases with age. In response to this finding, beginning in 2018 the CDC’s National Center for Health Statistics (NCHS) restricted use of the checkbox for determining cause of death to women aged 10-44. NCHS says it still suspects overcounts despite this adjustment and that data improvement is ongoing.

Evaluations by NCHS find that nearly the entire increase in mortality rates between 2003 and 2017 can be attributed to these changes and therefore don’t reflect an actual increase in deaths. According to NCHS, “The increase in maternal mortality in the United States is not likely due to a true increase in the underlying extent of maternal mortality. Rather, the majority of the observed increase in the maternal mortality rate is attributed to changes in data collection methods.”

We should note that measurement changes account for the major increase in mortality in 2017, but likely not for the subsequent increases in 2019 to 2021. Increases in 2020 and 2021 were almost entirely attributable to the COVID-19 pandemic, which we’ll discuss below. However, there does seem to have been a slight uptick in maternal mortality between 2018 and 2019, likely unrelated to measurement changes or the pandemic. And despite these explanations for recent increases in maternal mortality, bear in mind that the U.S. still has a significantly higher maternal mortality rate than other high-income countries.

Severe maternal morbidity (SMM) is measured using the World Health Organization’s International Classification of Diseases (ICD), Version 10 coding system, which classifies human diseases worldwide. This system identifies SMM through 21 conditions, each with specific codes used by health care providers. In 2015, the CDC transitioned from ICD-9 to ICD-10, which added complexities to the coding process and may have led to variations in coding quality and accuracy, ultimately affecting reported SMM rates. While the coding switch wasn’t the main reason for the nationwide rise in SMM, one study found it might partly explain the increase in Massachusetts, where SMM rates rose from 62.2 per 10,000 deliveries in 2014 to 74.6 in 2015. Because studies don’t indicate the magnitude of this effect, we can’t say with the same level of certainty that SMM rate increases are due to the measurement transition as we can for the maternal mortality rate increases.

SMM rates also vary based on the definition used. As noted above, the CDC uses 21 indicators to define SMM, including 16 conditions and five proceduresiv. Procedures, like blood transfusions, are included because they indicate severe conditions. However, blood transfusion is the most prevalent indicator of SMM and accounted for most of the increase in SMM rates in the U.S. between 1993 and 2014, obscuring trends in other indicators. To account for this, many definitions exclude blood transfusions and use only the remaining 20 indicators. All analyses of severe maternal morbidity in this brief exclude blood transfusions, so they don’t explain the increases in maternal morbidity in Massachusetts.

It’s also important to note that the CDC’s definition of severe maternal morbidity only accounts for serious complications during delivery hospitalizations. This excludes complications during pregnancy and postpartum, when risk of complications also run high, meaning SMM as a measure misses lots of complications during these stages of pregnancy.

What are likely real-world drivers of increasing maternal morbidity and mortality?

While it’s clear that measurement changes have driven much of the observed increases, especially in maternal mortality, there’s been a good deal of research on other real-world factors that have played some role. Better understanding these factors is perhaps the most pressing piece of this work as they suggest clear action steps for improving maternal well-being.

Many factors contribute to severe maternal morbidity and mortality, but here we focus only on factors that plausibly could have contributed to increases over the past decade or so. These include increases in opioid use disorder, increasing maternal age, increases in obesity and other chronic conditions, increasing deliveries by cesarian section, and the COVID-19 pandemic.

Increases in opioid use disorder

The rise in opioid use disorder (OUD) has coincided with increases in maternal mortality and morbidity. At the national level, a study by Arlyn Horn and Margaret Adgent found that mothers who filled two or more opioid prescriptions in the 41 days postpartum had a mortality rate approximately double that of mothers who did not (120.5 versus 57.7 per 100,000 person-years).

Research in Massachusetts reflects these trends. A study by Godwin K. Osei-Poky, Julia C. Prentice and co-authors found that between 2016 and 2020 Massachusetts residents with OUD had 2.12 times the risk of experiencing severe maternal morbidity, such as cardiac events, renal failure, and sepsis, compared to those without OUD (148 versus 88 per 10,000 deliveries). The authors hypothesize that pulmonary and cardiac complications were likely related to an overdose that then led to the mother needing to give birth emergently for her safety and the safety of the baby; that people with OUD are at higher risk of infections from injection drug use; and people with OUD may have inconsistent prenatal care leading to delays in diagnosis of conditions like preeclampsia.

Another report by the Massachusetts Department of Public Health on pregnancy-associated deaths from 2005 to 2014 revealed a substantial increase in deaths related to substance use, particularly opioids. By 2014, substance use was linked to about 40 percent of all pregnancy-associated deaths, with most occurring between 42 days and one year postpartum—outside the World Health Organization’s standard definition of “maternal mortality.” These findings underscore the urgent need for targeted health-care interventions and robust support systems to address the complex challenges faced by mothers with OUD, both during and beyond the immediate postpartum period.

Increasing maternal age

Women have been having babies at older ages, which can lead to a higher risk of complications during pregnancy and childbirth. Older maternal age—especially over the age of 35—is associated with a greater likelihood of chronic conditions such as hypertension, diabetes, and obesity, which can contribute to SMM. Women in this age group are also more likely to have a cesarean section and have multiples (e.g., twins), which put the mother’s health at greater risk.

In 2022, the average maternal age in Massachusetts was 32, up from 30 in 2011. Since 1970, the number of Massachusetts births to women younger than 30 years has steadily decreased while the number of births to women older than 30 years has increased. In the mid-1990s, it became more common for women in Massachusetts to give birth over the age of 30.

Between 2011 and 2020, Massachusetts women over 40 had the highest rates of SMM. In 2020 alone, women over 40 experienced SMM at a rate of 218.3 per 10,000 deliveries. Meanwhile, the rates of SMM were 108.2 per 10,000 deliveries for women between the ages of 35 to 39, 96.1 for women 30-24, and 77.1 for women younger than 30.

In terms of mortality, data from the CDC show that at the national level the maternal mortality rate for women over 40 is more than four times the rate for women between the ages of 25 and 39.

Increases in obesity and chronic health conditions

It is possible that more women are entering pregnancy with obesity or preexisting chronic conditions, such as hypertension and diabetes, putting them at greater risk of experiencing additional complications during pregnancy. If they are inadequately monitored and treated, these conditions can complicate pregnancy and lead to more severe outcomes.

Teasing out which of these varied chronic health conditions are truly on the rise and contributing to increased complications at birth (and which aren’t) is beyond the scope of this research brief. A look at obesity alone, however, suggests that it could be playing a role. According to the Massachusetts Behavioral Risk Factor Surveillance System, obesity among women increased from 21.4 percent in 2011 to 26.5 percent in 2022 and varies by race and maternal age. It’s hard to know what to make of the magnitude of this 5-percentage point increase, but the timing does coincide with the state’s increasing rate of SMM.

Increases in deliveries by cesarian section

The U.S. has a uniquely high rate of cesarean births, which carry a greater risk of complications compared to vaginal deliveries, including surgical infections, blood clots, and hemorrhage. More American women are having cesarean births for a variety of reasons including maternal requests for cesareans, concerns over medical liability, changes in maternal characteristics such as age and obesity, and a high rate of repeat cesarean deliveries after an initial cesarean. One caveat, however, is that the U.S. cesarean rate actually hasn’t increased significantly over the past decade or so when we’ve seen the greatest increases in SMM. It increased from about 20 percent in 1996 to a peak of 32 percent in 2009, and since then it has plateaued at around 31-32 percent. At the state level in Massachusetts, 31.8 percent of births were cesarean deliveries in 2021, and this rate was highest for Native American (34.4 percent) and Black (35.2 percent) women.

The COVID-19 pandemic

The COVID-19 pandemic explains basically all of the spike in maternal morbidity and mortality rates in 2020 and 2021, especially among Black and Latina women. When women who contracted COVID-19 were pregnant, their risk of severe illness or death were significantly higher due to physiologic changes related to pregnancy, such as decreased lung capacity and weakened immune system, and to COVID-19’s exacerbation of other health conditions, like diabetes or cardiovascular disease. The pandemic also caused delays in access to health care and worsened disparities in social determinants of health that contribute to poor maternal health, such as access to transportation or technology for telehealth.

According to a report by the U.S. Government Accountability Office (GAO) using CDC data, “COVID-related deaths—those for which COVID-19 is listed on the death certificate as a cause that contributed to death—accounted for most of the increase in maternal deaths in 2020, and all the increase in 2021.” COVID-19 was a contributing factor in 12 percent of maternal deaths in 2020 and 34 percent in 2021.

The GAO report also finds that Black and Latina women experienced higher rates of COVID-related maternal deaths. In 2020 and 2021 combined, the rate of COVID-related maternal deaths was 13.2 per 100,000 deliveries among Black women, 8.9 among Latina women, and 4.5 among White women. Because the COVID-19 pandemic is largely behind us, there is some reason for optimism that when data for 2022 and beyond becomes available it’ll show significant improvement back toward pre-pandemic levels.

Why are racial disparities so large, especially for Black women?

Regardless of the degree to which measurement changes have driven reported increases in maternal mortality and morbidity, large racial disparities persist. Further, simply referring to “racial disparities” misses some important nuance. As shown above, rates of severe maternal morbidity are meaningfully higher for Latina and AAPI women than for White women (111.9, 114.7, and 78 per 10,000 deliveries, respectively). But the rate of SMM for Black women is significantly higher at 190.8 per 10,000, or more than twice as high as the rate for White women. What factors likely explain these higher rates for birthing women of color, especially for Black women?

The factors we described above likely aren’t the leading factors behind the substantially higher rates for Black women. For example, Black women have the highest rates of severe maternal morbidity for every age group. This is true to the extent that between 2011 and 2022 Black women in their 20s in Massachusetts had higher rates of severe maternal morbidity than White women between the ages of 35 and 49, which is considered “advanced maternal age.”

Socioeconomic factors and disparities in social determinants of health

“Social determinants of health” refers to the general conditions prevalent where people are born, live, learn, work, and play. These factors affect a wide range of health, functioning, and quality-of-life outcomes and risks. While at first glance they seem non-medical, these interrelated factors ultimately have a significant impact on health outcomes and disparities, including maternal health.

Underlying the social determinants of health are centuries of structural racism and generations of inequity. Redlining, for example, was a racist business practice that led to worse health outcomes in predominantly Black neighborhoods. Not offering mortgages or insurance to support property ownership and upkeep meant decades of disinvestment in these neighborhoods and blocked economic advancement for their residents. To this day, once-redlined neighborhoods experience higher rates of housing instability, segregation, poverty, and negative health outcomes. Research has linked living in neighborhoods that were once redlined to higher risk of SMM, especially for Black women.

Black women are also more likely than women of other races to experience poverty, which is linked to higher rates of health issues that complicate pregnancy. Having lower incomes and living in high-poverty neighborhoods is associated with worse access to prenatal care and high-quality maternity services. That being said, the disparity exists across the income distribution. An analysis by the Massachusetts Health Policy Commission found that Black women are significantly more likely to experience SMM than White women even after accounting for community income level.

Housing instability is associated with poor maternal health outcomes as well. In Greater Boston, Black and Latina women are much more likely than White or Asian women to experience housing instability. Lacking stable housing can negatively affect mental health, raising the risk of SMM and death. Furthermore, where you live can affect maternal health outcomes through exposure to environmental contaminants, crime, interpersonal violence, and over-policing, all factors associated with poor maternal health outcomes.

Social determinants of health such as economic insecurity, lack of access to nutritious foods, and living in a built environment with low opportunity for physical activity can lead to physiological changes linked to higher rates of chronic conditions like hypertension and diabetes in communities of color, which put women at higher risk of SMM and death. While the Massachusetts Health Policy Commission finds that Black women are only slightly more likely than White women to have serious health conditions that could lead to pregnancy or delivery complications, Black women in Massachusetts have much higher rates of hypertension before pregnancy and during pregnancy, putting them at high risk for SMM.

Racism in maternal health care

Structural racism and implicit bias in the health-care system itself lead to disparities in the quality of care women receive and poorer health outcomes for women of color.

Structural factors like access to health care affect maternal health outcomes. In Massachusetts, we have much lower uninsured ratesv  and more women receive prenatal care than in most other states. Yet Black women in Massachusetts still receive prenatal care at lower rates than women of all other races. While 85 percent of White women in Massachusetts report receiving an adequate amount of prenatal care, only 72 percent of Black women do. Lack of access to care may be associated with the history of harm that the medical field has inflicted on Black communities, leading to greater mistrust of health systems.

The Massachusetts Health Policy Commission finds that 37 percent of Black women reported experiencing racism before delivery, 28 percent reported that their race contributed to stress, 31 percent reported feeling upset due to treatment based on their race, and 14 percent reported having physical symptoms due to treatment based on race.

Provider discrimination leads to worse maternal care for Black women. There has been ample reporting of maternal deaths and near misses among Black women whose providers failed to listen to their concerns, hindering diagnosis and treatment. Medical professionals may also hold harmful beliefs about biological differences between Black and White people that can influence the treatment they provide and contribute to racial disparities in pain assessment and treatment.

Experiences of racism or worry about being taken seriously due to race can cause immense stress for women of color during pregnancy and delivery, as shown above in the findings from the Massachusetts Health Policy Commission. This type of stress plays an important role in health deterioration and adverse pregnancy outcomes among Black women. For example, stress can increase the likelihood of experiencing hypertension during pregnancy, which can lead to severe maternal morbidity or mortality. Provider discrimination and structural racism directly contribute to racial disparities in maternal health outcomes.

Over time, maternal deaths have become almost entirely preventable. So, it's shocking that in 2024 some women in the U.S. still die in childbirth. And the already wide racial disparities appear to be growing. Despite the exaggeration in some outlets of a growing maternal health crisis, our maternal mortality and morbidity rates are unnecessarily high and there’s no question that we as a state must do more to improve the health and safety of women going through childbirth.

i. Note that throughout this brief we report rates as per 10,000 deliveries and 100,000 based on what was reported in the original source.

ii. Data collected by the OECD is the best available for international comparisons. However, it does not account for differences in how countries collect and report data, which means comparisons to other countries aren’t exact.  

iii. For SMM California ranked 46th, Colorado ranks 44th, and Minnesota ranked 43rd

iv. All analyses of severe maternal morbidity in this brief exclude blood transfusion and include the other 20 indicators.

v. In 2021 the uninsured rate in Massachusetts was 2.4 percent compared to the national rate of 9.2 percent according to the Massachusetts Center for Health Information and Analysis

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