Approximately 700 women die in the United States each year as a result of pregnancy
or its complications, and significant racial/ethnic disparities in pregnancy-related
mortality exist (
1
). Data from CDC’s Pregnancy Mortality Surveillance System (PMSS) for 2007–2016 were
analyzed. Pregnancy-related mortality ratios (PRMRs) (i.e., pregnancy-related deaths
per 100,000 live births) were analyzed by demographic characteristics and state PRMR
tertiles (i.e., states with lowest, middle, and highest PRMR); cause-specific proportionate
mortality by race/ethnicity also was calculated. Over the period analyzed, the U.S.
overall PRMR was 16.7 pregnancy-related deaths per 100,000 births. Non-Hispanic black
(black) and non-Hispanic American Indian/Alaska Native (AI/AN) women experienced higher
PRMRs (40.8 and 29.7, respectively) than did all other racial/ethnic groups. This
disparity persisted over time and across age groups. The PRMR for black and AI/AN
women aged ≥30 years was approximately four to five times that for their white counterparts.
PRMRs for black and AI/AN women with at least some college education were higher than
those for all other racial/ethnic groups with less than a high school diploma. Among
state PRMR tertiles, the PRMRs for black and AI/AN women were 2.8–3.3 and 1.7–3.3
times as high, respectively, as those for non-Hispanic white (white) women. Significant
differences in cause-specific proportionate mortality were observed among racial/ethnic
populations. Strategies to address racial/ethnic disparities in pregnancy-related
deaths, including improving women’s health and access to quality care in the preconception,
pregnancy, and postpartum periods, can be implemented through coordination at the
community, health facility, patient, provider, and system levels.
PMSS was established in 1986 by CDC and the American College of Obstetricians and
Gynecologists to better understand the causes of death and risk factors associated
with pregnancy-related deaths. Methodology of PMSS has been described previously (
2
). Briefly, CDC requests that all states, the District of Columbia, and New York City
identify deaths during or within 1 year of pregnancy and send corresponding death
certificates, linked birth or fetal death certificates, and additional data when available.
Medically trained epidemiologists review information and determine the relatedness
to pregnancy and cause for each death. A death was considered pregnancy-related if
it occurred during or within 1 year of pregnancy and was caused by a pregnancy complication,
a chain of events initiated by pregnancy, or aggravation of an unrelated condition
by the physiologic effects of pregnancy. U.S. natality files were the source of live
birth data (
3
).
PRMRs were analyzed by age group, highest level of education, and calendar year for
women who were non-Hispanic white, black, AI/AN, Asian or Pacific Islander (A/PI),
and Hispanic. Per the PMSS assurance of confidentiality, state-specific data are not
authorized to be released. States were anonymously classified by PRMR and grouped
into lowest, middle, and highest tertiles by PRMR; the PRMR was calculated by race/ethnicity
per state tertile. Disparity ratios (comparisons of PRMR between two racial/ethnic
groups) were calculated by five 2-year intervals, demographic characteristics, and
state PRMR tertiles. White decedents were the referent group because they represented
the largest racial/ethnic group. Cause-specific proportionate mortality was classified
in 10 mutually exclusive categories,* and differences by race/ethnicity were identified
using chi-squared tests. SAS statistical software (version 9.4; SAS Institute) was
used for the analyses.
During 2007–2016, a total of 6,765 pregnancy-related deaths occurred in the United
States (PRMR = 16.7 per 100,000 births). PRMRs were highest among black (40.8) and
AI/AN (29.7) women; these rates were 3.2 and 2.3 times the PRMR for white women (12.7)
(Table 1). From 2007–2008 to 2015–2016, the overall PRMR increased slightly from 15.0
to 17.0. The disparity ratios did not change significantly over time.
TABLE 1
Pregnancy-related mortality ratios (PRMRs) (pregnancy-related deaths per 100,000 live
births) and disparity ratios by age group, education, tertile of states, and race/ethnicity*
— United States, 2007–2016
†
Characteristic
Total PRMR
White PRMR
Black PRMR
Black: white disp. ratio
AI/AN PRMR
AI/AN: white disp. ratio
A/PI PRMR
A/PI: white disp. ratio
Hispanic PRMR
Hispanic: white disp. ratio
Total
16.7
12.7
40.8
3.2
29.7
2.3
13.5
1.1
11.5
0.9
Age group (yrs)
<20
10.9
10.8
16.8
1.5
19.5
1.8
—§
—
6.7
0.6
20–24
12.2
9.6
26.3
2.7
11.6
1.2
7.2
0.7
7.0
0.7
25–29
13.3
9.3
37.0
4.0
25.2
2.7
9.5
1.0
9.6
1.0
30–34
15.8
11.3
48.6
4.3
41.2
3.7
12.5
1.1
12.6
1.1
35–39
27.7
20.5
80.7
3.9
104.2
5.1
18.8
0.9
22.6
1.1
≥40
65.2
51.5
189.7
3.7
—
—
36.6
0.7
44.0
0.9
Education completed
Less than high school
21.6
25.0
45.6
1.8
50.8
2.0
18.7
0.7
12.6
0.5
High school
27.4
25.2
59.1
2.3
43.7
1.7
22.9
0.9
11.2
0.4
Some college
16.4
11.7
41.0
3.5
32.0
2.7
15.4
1.3
9.4
0.8
College graduate or higher
10.9
7.8
40.2
5.2
—
—
13.2
1.7
9.3
1.2
Period
2007–2008
15.0
11.5
35.6
3.1
26.9
2.3
11.4
1.0
10.8
0.9
2009–2010
17.3
12.8
41.6
3.2
30.7
2.4
13.6
1.1
12.8
1.0
2011–2012
16.8
12.4
44.3
3.6
38.4
3.1
11.6
0.9
10.4
0.8
2013–2014
17.6
13.5
42.1
3.1
30.3
2.2
15.8
1.2
12.0
0.9
2015–2016
17.0
13.2
40.8
3.1
21.9
1.7
14.7
1.1
11.6
0.9
State-level PRMR tertile
Lowest PRMR
10.7
8.7
26.0
3.0
28.9
3.3
11.9
1.4
9.7
1.1
Middle PRMR
15.4
11.0
36.9
3.3
33.9
3.1
14.2
1.3
11.7
1.1
Highest PRMR
21.9
16.6
45.9
2.8
28.8
1.7
15.8
0.9
13.2
0.8
Abbreviations: AI/AN = American Indian/Alaska Native; A/PI = Asian/Pacific Islander.
* Blacks, whites, AI/AN, and A/PI were non-Hispanic; Hispanic women might be of any
race.
† 25 pregnancy-related deaths with unknown race/ethnicity were included in the total
analyses but not presented in an individual column; two pregnancy-related deaths with
unknown age were excluded from age analyses; 687 pregnancy-related deaths with unknown
educational levels were excluded from education analyses.
§ Dashes indicate fewer than 10 deaths; these results were suppressed because ratios
might be unreliable.
PRMR increased with maternal age; the black:white disparity was lowest among women
aged <20 years (1.5) and highest among those aged 30–34 years (4.3); the AI/AN:white
disparity was lowest among women aged 20–24 years (1.2) and was highest among women
aged 35–39 years (5.1). Racial/ethnic disparities were present at all education levels.
The PRMR among black women with a completed college education or higher was 1.6 times
that of white women with less than a high school diploma. Among women with a college
education or higher, the PRMR for black women was 5.2 times that of their white counterparts.
The black:white disparity ratio in the PRMR for the states in the lowest, middle,
and highest tertiles was 3.0, 3.3, and 2.8, respectively.
Cardiovascular conditions (including cardiomyopathy, other cardiovascular conditions,
and cerebrovascular accidents), other noncardiovascular medical conditions, and infection
were leading causes of pregnancy-related deaths. The proportion of pregnancy-related
deaths attributed to each of 10 mutually exclusive causes varied by race/ethnicity
(Table 2). Cardiomyopathy, thrombotic pulmonary embolism, and hypertensive disorders
of pregnancy contributed to a significantly higher proportion of pregnancy-related
deaths among black women than among white women. Hemorrhage and hypertensive disorders
of pregnancy contributed to a higher proportion of pregnancy-related deaths among
AI/AN women than among white women.
TABLE 2
Cause-specific pregnancy-related mortality, by race/ethnicity — Pregnancy Mortality
Surveillance System, United States, 2007–2016
Cause of death
Proportionate cause of death by race/ethnicity* No. (%) attributed to each cause
Total deaths
White
Black
AI/AN
A/PI
Hispanic
Hemorrhage
250 (9.1)
237 (9.7)
23 (19.7)†
66 (19.5)†
173 (15.8)†
752 (11.1)
Infection
418 (15.2)
235 (9.7)§
10 (8.5)§
51 (15.0)
183 (16.7)
900 (13.3)
Amniotic fluid embolism
147 (5.3)
106 (4.4)
3 (2.6)
51 (15.0)†
58 (5.3)
365 (5.4)
Thrombotic pulmonary or other embolism
246 (8.9)
265 (10.9)†
9 (7.7)
11 (3.2)§
88 (8.0)
624 (9.2)
Hypertensive disorders of pregnancy
184 (6.7)
200 (8.2)†
15 (12.8)†
21 (6.2)
106 (9.7)†
528 (7.8)
Anesthesia complications
7 (0.3)
14 (0.6)
0 (0.0)
3 (0.9)
6 (0.5)
30 (0.4)
Cerebrovascular accidents
207 (7.5)
148 (6.1)§
6 (5.1)
37 (10.9)†
92 (8.4)
490 (7.2)
Cardiomyopathy
288 (10.4)
345 (14.2)†
17 (14.5)
21 (6.2)§
75 (6.8)§
748 (11.1)
Other cardiovascular conditions
465 (16.9)
393 (16.2)
13 (11.1)
38 (11.2)§
124 (11.3)§
1,035 (15.3)
Other noncardiovascular medical conditions
384 (13.9)
343 (14.1)
16 (13.7)
26 (7.7)§
130 (11.9)
903 (13.3)
Unknown
160 (5.8)
146 (6.0)
5 (4.3)
14 (4.1)
61 (5.6)
390 (5.8)
Total
2,756
2,432
117
339
1,096
6,765¶
Abbreviations: AI/AN = American Indian/Alaska Native; A/PI = Asian/Pacific Islander.
* Black, white, AI/AN, and A/PI women were non-Hispanic; Hispanic women could be of
any race.
† Significantly higher proportion of pregnancy-related deaths compared with that among
white women, p<0.05.
§ Significantly lower proportion of pregnancy-related deaths compared with that among
white women, p<0.05.
¶ Twenty-five pregnancy-related deaths with unknown race/ethnicity were included in
the total but not elsewhere in the table.
Discussion
Racial/ethnic disparities in pregnancy-related mortality were evident in 2007 and
continued through 2016, with significantly higher PRMRs among black and AI/AN women
than among white, A/PI, and Hispanic women. The PRMR for black and AI/AN women aged
≥30 years was approximately four to five times that of their white counterparts. Even
in states with the lowest PRMRs, and among groups with higher levels of education,
significant disparities persisted, demonstrating that the disparity in pregnancy-related
mortality for black and AI/AN women is a complex national problem.
Multiple factors contribute to pregnancy-related mortality and to racial/ethnic disparities.
Previous analyses found that for each pregnancy-related death, an average of three
to four contributing factors were identified at multiple levels, including community,
health facility, patient/family, provider, and system (
1
). Thirteen state maternal mortality review committees reported 60% of pregnancy-related
deaths were preventable, and there were no significant differences in preventability
by race/ethnicity (
1
). Differences in proportionate causes of death among black and AI/AN women might
reflect differences in access to care, quality of care, and prevalence of chronic
diseases (
4
).
Chronic diseases associated with increased risk for pregnancy-related mortality (e.g.,
hypertension) are more prevalent and less well controlled in black women (
5
). Ensuring access to quality care, including specialist providers, during preconception,
pregnancy, and the postpartum period is crucial for all women to identify and manage
chronic medical conditions (
4
). Systemic factors (e.g., gaps in health care coverage and preventive care, lack
of coordinated health care, and social services) and community factors (e.g., securing
transportation for medical visits and inadequate housing) have also been identified
as contributors to pregnancy-related deaths (
1
). Addressing these factors and ensuring that pregnant women at high risk for complications
receive care in facilities prepared to provide the required level of specialized care
can improve outcomes.
†
,
§
In addition, innovative delivery of care models in the preconception, pregnancy, and
postpartum periods might be further evaluated for their potential to reduce maternal
disparities.
Quality of care likely has a role in pregnancy-related deaths and associated racial
disparities. A national study of five specific pregnancy complications found a similar
prevalence of complications among black and white women, but a significantly higher
case-fatality rate among black women (
6
). Studies have suggested that black women are more likely than are white women to
receive obstetric care in hospitals that provide lower quality of care (
7
). Hospitals and health care systems can implement standardized protocols and training
in quality improvement initiatives, ensuring implementation in facilities that serve
disproportionately affected communities. Quality improvement efforts, such as perinatal
quality collaboratives
¶
that facilitate a change in the culture of care provision, implement standards of
care,** and rapidly use data to identity opportunities for improvement, can improve
the quality of care received by all pregnant and postpartum women.
Implicit racial bias has been reported in the health care system and can affect patient-provider
interactions, treatment decisions, patient adherence to recommendations, and patient
health outcomes (
8
). This report’s findings demonstrate that black and AI/AN women have a more accelerated
trajectory in age-specific PRMRs compared with white women. This might be related
to the “weathering” hypothesis, which proposed that black women experience earlier
deterioration of health because of the cumulative impact of exposure to psychosocial,
economic, and environmental stressors (
9
). Identifying and addressing implicit bias and structural racism in health care and
community settings, engaging communities in prevention efforts, and supporting community-based
programs that build social support and resiliency would likely improve patient-provider
interactions, health communication, and health outcomes (
4
).
Reducing disparities in pregnancy-related mortality requires addressing multifaceted
contributors. Ensuring robust comprehensive data collection and analysis through state
and local maternal mortality review committees, which thoroughly review pregnancy-related
deaths and make actionable prevention recommendations, offer the best opportunity
for identifying priority strategies to reduce disparities in pregnancy-related mortality.††
The findings in this report are subject to at least three limitations. First, PMSS
predominantly uses death certificates and linked birth or fetal death certificates
to determine the pregnancy-relatedness of each death. Errors in reported pregnancy
status on death certificates have been described, potentially leading to overestimation
of the number of pregnancy-related deaths (
10
). Second, pregnancy-relatedness cannot generally be determined in PMSS for cancer-related
deaths or injury deaths such as drug overdoses, suicides, or homicides, and thus,
these are often not included in the PRMR calculated from PMSS data. Finally, small
cohort sizes precluded the reporting of some factors by race/ethnicity; in addition,
there might be inconsistencies in the reporting of race/ethnicity when death certificates
were used for classification.
§§
Most pregnancy-related deaths can be prevented, and significant racial/ethnic disparities
in pregnancy-related mortality need to be addressed. Further identification and evaluation
of factors contributing to racial/ethnic disparities are crucial to inform and implement
prevention strategies that will effectively reduce disparities in pregnancy-related
mortality, including strategies to improve women’s health and access to quality care
in the preconception, pregnancy, and postpartum periods. Addressing this complex national
problem requires coordination and collaboration among community organizations, health
facilities, patients and families, health care providers, and health systems.
Summary
What is already known about this topic?
Approximately 700 women die annually in the United States as a result of pregnancy
or its complications; racial/ethnic disparities exist.
What is added by this report?
During 2007–2016, black and American Indian/Alaska Native women had significantly
more pregnancy-related deaths per 100,000 births than did white, Hispanic, and Asian/Pacific
Islander women. Disparities persisted over time and across age groups and were present
even in states with the lowest pregnancy-related mortality ratios and among groups
with higher levels of education. The cause-specific proportion of pregnancy-related
deaths varied by race/ethnicity.
What are the implications for public health practice?
Identifying factors that drive differences in pregnancy-related deaths and implementing
prevention strategies to address them could reduce racial/ethnic disparities in pregnancy-related
mortality. Strategies to address racial/ethnic disparities in pregnancy-related deaths,
including improving women’s health and access to quality care in the preconception,
pregnancy, and postpartum periods, can be implemented through coordination at the
community, health facility, patient and family, health care provider, and system levels.