In the U.S., more than 80 percent of pregnancy-related deaths are preventable. Yet for many years, the nation has had the highest maternal mortality rate among high-income countries. And that rate continued to rise between 2018 and 2022, with large disparities by state, race, and ethnicity, a new study reports.

A team of researchers at the National Institutes of Health, in collaboration with Associate Professor Rose Molina of Harvard Medical School, used data from the Centers for Disease Control and Prevention to study pregnancy-related deaths in that four-year period.

The sharpest rate increase occurred in 2021, likely reflecting the onset of the COVID-19 pandemic in 2020. While the rates then lowered, they were still higher in 2022 (32.6 deaths per 100,00 live births) than they were in 2018 (25.3 deaths per 100,000 live births).

The results were consistent with past research that has demonstrated significant disparities across racial groups. American Indian and Alaska Native women had the highest mortality rate (106.3 deaths per 100,000 live births), nearly four times higher than the rate among white women (27.6 deaths per 100,000 live births), followed by non-Hispanic Black women (76.9 deaths per 100,00 live births).

State rates also varied greatly, ranging from 18.5 to 59.7 deaths per 100,000 live births.

In this edited conversation, Molina, an obstetrician-gynecologist, discusses the findings and what needs to happen next.

Why is pregnancy-related death much higher in the U.S. than other high-income countries?

There are many reasons: our patchwork healthcare system, inequitable policies, maternity care deserts, as well as persistent systems of bias and discrimination across racial and ethnic groups. It’s the way in which the healthcare system is designed. There are also signals that reproductive-age individuals are experiencing more chronic medical conditions, including cardiovascular disease, at younger ages than before.

The results showed some significant racial disparities in maternal mortality rates. Was that surprising?

While I am saddened that the racial inequities have persisted, the reality is that this has been demonstrated over and over again in the literature. There have been some innovations aimed at reducing inequities between racial groups in health systems. But at a population level, as a country, we’re not seeing meaningful improvement yet.

Our study points to different policy levers that need to be addressed, because there shouldn’t be as much state-level variation as there is. One of our biggest findings is that we could have avoided 2,679 pregnancy-related deaths during this time period if the national rate were that of California. If California can do it, then how can we get other states to perform as well?

The overall leading cause of death in your study was cardiovascular disease, which accounted for just over 20 percent of deaths. Has that always been the case?

Over the decades in the U.S., we’ve seen a transition from hemorrhage to cardiovascular disease as the leading cause of pregnancy-related death. Cardiovascular disease encompasses a range of disorders: hypertension, pre-eclampsia, eclampsia, and peripartum cardiomyopathy, cardiac arrest, and stroke.

One reason for the shift may be that more and more people have chronic hypertension. We saw that the highest increased rate of pregnancy-related death was actually in the middle-age group (those 25 to 39), not the highest-age group. Therefore, one of the potential concerns is that chronic diseases like hypertension are affecting younger people. It’s been much more common to have hypertension if you’re 40 or older. But we’re beginning to see more hypertension at an earlier age.

In fact, pregnancy-related death increased for all age groups between 2018 and 2022. How significant is that rise?

It’s only four years, and the studied time period spanned the initial part of the COVID pandemic. But there’s still enough evidence that we should be paying more attention to this increase. Even in 2022, the rates were higher than in 2018. And the rates were already rising in 2019, before the pandemic started.

You also found that “late maternal deaths” — those that occur between 42 days and 1 year after pregnancy — accounted for nearly a third of the total. Yet the World Health Organization does not include late maternal death in its definition of pregnancy-related mortality. Why is it important to consider this time period?

Internationally, any death during pregnancy and up to 42 days after birth is considered a maternal mortality. In the U.S., we’re moving toward being inclusive of the full year after birth, because the 42 days postpartum is somewhat arbitrary.

There’s a growing recognition that the postpartum period doesn’t just end on a cliff at six weeks, even though that’s how many of our healthcare systems are designed, but rather postpartum recovery should be treated as a continuum. The high number of late maternal deaths points to why we need to design better systems of healthcare in those later months, as opposed to only focusing on the first six to 12 weeks.

Rose Molina.

Veasey Conway/Harvard Staff Photographer

This study offers a fuller picture of the problem than past tallies. Can you talk a bit about that?

One of the biggest challenges in tracking maternal deaths in the United States is that we didn’t actually have a national system for tracking these deaths consistently until 2018, because that’s when the full implementation of the pregnancy checkbox on death certificates went into full effect across the 50 states.

What that means is that when someone dies, the death certificate now has a pregnancy check box, so there can be some indication as to whether the person who passed away was pregnant at the time. However, it took a long time for all states to fully implement that. That’s why our data is so interesting, because we looked at the data starting in 2018, when that process was fully implemented across the 50 states.

Now that everything is laid out, how can these numbers be improved? What needs to happen next?

The biggest take-home message is that we need to continue to invest in public health infrastructure. It’s very clear that we’re not getting better, and if anything, the rates of pregnancy-related deaths are getting worse. So we need to change something about how we are addressing this.

In particular, we need to increase investment in innovative solutions to address quality of care during pregnancy and the extended postpartum period. At the state level, we really need to be addressing policy differences and trying to understand why certain states fare so much worse than other states.

It’s a concerning moment because the public health infrastructure to track these deaths is at risk. Research dollars are being cut dramatically. Pregnancy is being deprioritized. These actions and cuts threaten any work trying to improve maternal health outcomes, which can help inform policy at the state level and advocacy to enhance access to quality full-spectrum pregnancy care.