Cardiovascular-related maternal mortality has more than doubled since 1999

The rate of maternal mortality related to cardiovascular causes more than doubled between 1999 and 2022 in the United States, according to a study being presented at the American College of Cardiology's Annual Scientific Session (ACC.25).

The finding is concerning, especially as the U.S. has the highest overall rate of maternal mortality among all developed countries, researchers said. Since cardiovascular problems are a leading cause of death around the time of pregnancy and childbirth, the new findings shed light on the drivers behind recent trends and draw attention to particularly high rates of mortality seen among Black women and those living in Southern states.

We're heading in the wrong direction. The United States is supposed to be a global leader in advancing health and medicine, and the fact that we still have pregnant women who are dying-often because of preventable causes-should sound alarm bells. The fact that there are disparities based on race means we need to pay better attention to more vulnerable populations, specifically Black women."

Mohammad Ahabab Hossain, MD, study's lead author and resident physician at Rutgers New Jersey Medical School in Newark, New Jersey

Maternal mortality refers primarily to deaths that occur when a person is pregnant or has recently given birth. It can also include deaths that occur up to a year after giving birth, if the cause of death is linked to having been pregnant.

For the study, researchers used data from the U.S. Centers for Disease Control and Prevention WONDER database collected between 1999-2022 to analyze rates of maternal mortality attributed to conditions such as high blood pressure, conditions related to dangerous blood clots and conditions that weaken the heart's pumping ability. They divided the number of cardiovascular-related maternal deaths by the total number of women of reproductive age to calculate the rate of cardiovascular-related maternal mortality for each year, adjusted by age.

The results showed that the rate of maternal mortality from cardiovascular disease rose from 3.6 per 1 million individuals in 1999 to a peak of 10.5 per million in 2021 and then decreased slightly to just under 9.1 per million in 2022. In terms of absolute numbers, those rates translate to hundreds of deaths per year. For example, in 2022, it is estimated that about 600 U.S. women died from cardiovascular causes, such as peripartum cardiomyopathy, hypertensive disorders of pregnancy and heart attack, around the time of pregnancy.

The data showed especially high rates of maternal mortality in 2020 and 2021, which researchers said may have been due to limited access to prenatal care or a hesitancy to visit medical clinics during the peak of the COVID-19 pandemic. Researchers noted that the greatest year-over-year increase was seen in 2018, which they attributed to the nationwide adoption of standardized reporting of pregnancy status on death certificates, which began in 2003 and expanded to all 50 states by 2018.

"While the addition of the pregnancy checkbox on death certificates complicates the comparison of maternal mortality pre- and post-2018, what remains certain is that maternal deaths due to cardiovascular causes remain unacceptably high," Hossain said.

Researchers also compared rates of cardiovascular-related maternal mortality during more recent years (2018-2022) by race and geographic region. During this period, Black women had about triple the rate of maternal mortality as White women, with a mortality rate of 21.9 per million among Black women versus 7.1 per million among White women. Those living in the South saw the highest mortality rate of any U.S. region, with a mortality rate of 12.1 per million compared with 5.4 per million in Western states.

Factors such as socioeconomic disadvantages, limited access to health care, higher prevalence of risk factors and issues with trust in the health care system, especially among Black people, likely play a role in creating disparities, researchers said. Increasing rates of health conditions related to cardiovascular problems may have also contributed to the rise in rates of cardiovascular-related maternal mortality in the U.S. population as a whole over time.

"Part of the reason this is happening is because heart disease and hypertension are becoming more and more prevalent, as are the conditions that are connected to heart disease, like diabetes and obesity. As a result, we wind up with more high-risk pregnancies," Hossain said. "However, a lot of this is preventable. If a patient has a history of hypertension or other preexisting cardiovascular disease, that patient should be connected with a high-risk obstetrics clinic to receive the care they need."

To help prevent maternal deaths, Hossain said it is important for both clinicians and patients to recognize that having cardiovascular risk factors can lead to serious problems during and after pregnancy. Being aware of these factors and taking steps to control them-for example, by getting blood pressure under control and managing diabetes-can help to prevent complications. Awareness of these risk factors can also inform preconception counseling.

Increasing access to prenatal care at clinics that are equipped to handle high-risk pregnancies is key to reducing disparities, Hossain said, noting that this requires a team effort bringing together obstetricians, cardiologists, nursing staff and social workers. Better access to care is also important after childbirth, since some women experience health problems related to their pregnancy even after the baby is born, he said.

One limitation of the study was that maternal mortality was calculated as a ratio of the number of cardiovascular-related maternal deaths divided by the total number of women of childbearing age in each year, which includes all women ages 15-44 and not only those who became pregnant. The calculated rates would be higher if maternal mortality were compared against the total number of pregnancies that occurred in each year.