Pregnancy Mortality Surveillance System

What to know

The Centers for Disease Control and Prevention (CDC) conducts national surveillance to better understand the causes of pregnancy-related deaths. The Pregnancy Mortality Surveillance System (PMSS) defines a pregnancy-related death as a death during or within 1 year of the end of pregnancy from any cause related to or aggravated by the pregnancy. Medical epidemiologists review and analyze applicable vital records, and additional available data from all 50 states, New York City, and Washington, DC. Beginning in 2020, data from Puerto Rico are included, and in 2021, data from Northern Mariana Islands are included in PMSS.

Pregnancy Mortality Surveillance System logo with icon of pregnant woman

Pregnancy-related deaths data

Figure 1. Pregnancy-related mortality ratio in the United States: 1987-2021

Data from PMSS and birth records from the National Vital Statistics System (NVSS) via CDC Wide-Ranging Online Data for Epidemiologic Research (WONDER) are used to calculate the pregnancy-related mortality ratio (PRMR), an estimate of the number of pregnancy-related deaths for every 100,000 live births.

Since PMSS was implemented, the number of reported pregnancy-related deaths in the United States increased from 7.2 deaths per 100,000 live births in 1987 to 33.2 deaths per 100,000 live births in 2021. The graph above shows PRMRs between 1987 and 2021 (the latest available year of data). The addition of Puerto Rico and Northern Mariana Islands to PMSS does not explain the increase in the PRMR from 2019 to 2021.

Pregnancy-related deaths by race-ethnicity

Considerable racial-ethnic disparities in pregnancy-related mortality exist,12 and these disparities increased during 2020 and 2021.

Figure 2. Pregnancy-related mortality ratio by race-ethnicity: 2017–2019, 2020, and 2021a,b

In 2017–2019, the highest PRMR was among non-Hispanic Native Hawaiian or Other Pacific Islander persons. In 2020 and 2021, the highest PRMR was among non-Hispanic American Indian or Alaska Native persons. Non-Hispanic Black persons are also disproportionately impacted by pregnancy-related deaths. Variability in the risk of death by race-ethnicity may be due to several factors including differences in access to care, quality of care, prevalence of chronic diseases, and other factors that impact health.34

Causes of pregnancy-related deaths

Figure 3. Causes of pregnancy-related deaths in the United States: 2017–2019, 2020, and 2021a

Spotlight‎

Infection was the most frequent underlying cause of pregnancy-related deaths in 2020 and 2021, driven by pregnancy-related COVID-19 deaths.

A new cause of death code specific for COVID-19, within the infection category, was used during PMSS review of deaths occurring in 2020. In 2021, infection was the most frequent underlying cause of death (48.8%) and COVID-19 accounted for 40.5% of all pregnancy-related deaths.

The number of pregnancy-related deaths with an underlying cause of COVID-19 in 2021 (N=495) was nearly four times higher than in 2020 (N=133).

Pregnant and postpartum persons are more likely to get very sick from COVID-19 compared to those who are not pregnant.56 In addition, studies show that an increasing number of pregnant persons in the United States have chronic health conditions such as hypertension,78 diabetes,89 and chronic heart disease.10 These conditions may put a person at higher risk of complications during or within 1 year of the end of pregnancy.

Pregnancy-related deaths by urban-rural classifications

Figure 4. Pregnancy-related mortality ratio by urban-rural classificationsa: 2017–2019, 2020, and 2021

Spotlight‎

In 2021, the highest pregnancy-related mortality ratios were found among people residing in the most rural classifications.

Figure 4 shows PRMRs per 100,000 live births by urban-rural classifications using the 2013 National Center for Health Statistics Urban-Rural Classification Scheme for Counties. Data were geocoded using the Texas A&M Geoservices' Batch Geocoding. Metropolitan counties, such as large central, large fringe, medium, and small, can be considered urban. Micropolitan and noncore counties can be considered rural.

A prior study found that PRMRs were higher in noncore (the most rural categorization) counties when compared to metropolitan counties.11 Variability in the risk of death by geographic location groups might reflect chronic health conditions and access to care, including risk-appropriate care.1213  For example, residents of rural areas may face challenges such as distance from and lack of access to obstetric services and providers.

Pregnancy-related deaths by age

Figure 5. Pregnancy-related mortality ratio by maternal agea: 2017–2019, 2020, and 2021b

Spotlight‎

In 2021, pregnancy-related mortality ratios were higher among older age groups.

Figure 5 shows PRMRs per 100,000 live births by maternal age group. Variability in the risk of death by maternal age may be due to several factors including a higher risk of pregnancy complications and prevalence of chronic diseases.14

Pregnancy-related deaths by HHS Region

Figure 6. Pregnancy-related mortality ratio by HHS Regiona: 2017–2019, 2020, and 2021b

Spotlight‎

In 2021, there was wide variation in pregnancy-related mortality by HHS regions.

Figure 6 presents PRMRs per 100,000 live births by regions defined by U.S Department of Health and Human Services (HHS). The highest pregnancy-related mortality ratios are in Regions 4 and 6.

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Content Source:
National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP); Division of Reproductive Health
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