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Office of the Surgeon General (OSG). The Surgeon General’s Call to Action to Improve Maternal Health [Internet]. Washington (DC): US Department of Health and Human Services; 2020 Dec.
MATERNAL MORTALITY
Despite having one of the most technologically advanced health care systems in the world, the U.S. continues to have unacceptably high rates of maternal mortality.4 In 2018, for every 100,000 live births, approximately 17 women died while pregnant or within 42 days of the end of pregnancy from causes related to pregnancy or delivery.5
In the United States, maternal mortality is measured in multiple ways by different data collection systems (Appendix A). While “maternal deaths”6 refer to deaths occurring during pregnancy or within 42 days of the end of pregnancy, the term “pregnancy-related death”7 includes deaths occurring during pregnancy and up to one year after pregnancy. Between 2011 and 2015, 31.3% of pregnancy-related deaths occurred during pregnancy, 16.9% on the day of delivery, 18.6% on days 1–6 postpartum, 21.4% 7–42 days postpartum, and 11.7% 43–365 days postpartum (Figure 1).8,9 Overall, approximately two out of three pregnancy-related deaths are considered preventable.10
FIGURE 1
Pregnancy-related deaths by time of death relative to the end of pregnancy – Pregnancy Mortality Surveillance System, U.S., 2011–2015.
MATERNAL DEATHS
Deaths of women while pregnant or within 42 days of the end of pregnancy, from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes. Late maternal deaths (occurring between 43 days and 1 year of death) are not included as part of the WHO definition of maternal mortality
PREGNANCY-RELATED DEATHS
Deaths that occur while pregnant or within one year of the end of pregnancy from a cause related to pregnancy or its management, but not from accidental or incidental causes
From 2011 to 2015, the most common causes of pregnancy-related deaths in the U.S. were cardiovascular conditions, accounting for more than 1 in 3 pregnancy-related deaths.8
Causes of pregnancy-related death vary depending on when the death occurs. In 2011–2015, the most common causes of death on the day of delivery were hemorrhage (excessive bleeding) and amniotic fluid embolism (when amniotic fluid enters a mother’s bloodstream) (Figure 2).8 Hemorrhage, hypertensive disorders of pregnancy (gestational hypertension, preeclampsia, eclampsia/seizures), and infection were leading causes of death during the first 6 days after delivery. During pregnancy, leading causes included “other non-cardiovascular medical conditions” (e.g., blood disorders, immune disorders, kidney disease), “other cardiovascular conditions”, (e.g., congenital heart disease, ischemic heart disease), and infection. Causes of death between 7 to 42 days after delivery included infection, cardiovascular conditions, and cerebrovascular accidents (stroke). From 43 days through the end of the first year after delivery, cardiomyopathy (weakness of the heart muscle) was the leading cause of pregnancy-related death.
FIGURE 2
Pregnancy-related deaths by cause of death and time of death relative to the end of pregnancy – Pregnancy Mortality Surveillance System, U.S., 2011–2015.
CARDIOVASCULAR CONDITIONS
Cardiomyopathy
Cerebrovascular accidents
Other cardiovascular conditions (congenital heart disease, ischemic heart disease, heart valve disease, hypertensive heart disease, and congestive heart failure)
Over the past two decades, the contribution of hemorrhage, hypertensive disorders of pregnancy, and anesthesia complications to pregnancy-related deaths have declined, while the contribution of cardiovascular conditions has increased.8,11,12
SEVERE MATERNAL MORBIDITY
Thousands of women experience unintended outcomes of labor and delivery that result in significant short- or long-term consequences to their health.13 These complications are referred to as severe maternal morbidity (SMM) and include eclampsia, sepsis, or hysterectomy, to name a few.14 Blood transfusions (procedure in which a patient is given donated blood) are significant events and can be an indicator of SMM, although they may not always reflect SMM in the absence of other indicators.15,16 As a result of this and changes in data reporting,1 recent SMM estimates and those provided in this Call to Action do not include those who only received blood transfusions.
In 2017, there were over 25,000 hospital deliveries with an SMM (not including those who only received a blood transfusion),2 and the five most common complications were disseminated intravascular coagulation (clotting and bleeding disorder), hysterectomy (surgical removal of the uterus), acute kidney failure, sepsis (severe infection), and adult respiratory distress syndrome. When those with blood transfusions alone are included, the number of hospital deliveries with an SMM more than doubles.3
SEVERE MATERNAL MORBIDITY
Unintended outcomes of labor and delivery that result in significant short-term or long-term consequences to a woman’s health
DIFFERENCES IN MATERNAL MORTALITY AND MORBIDITY AND CONTRIBUTING FACTORS
There are significant differences in the rates of pregnancy-related mortality and SMM in the U.S., including by race and ethnicity, education, geography, and age. Understanding and addressing the factors that contribute to these differences can improve maternal health across the U.S.
SOCIODEMOGRAPHIC AND GEOGRAPHIC DIFFERENCES
RACE AND ETHNICITY
Maternal health disparities exist and are especially marked for some racial and ethnic minority women. In particular, non-Hispanic black and American Indian/Alaska Native (AI/AN) women have higher rates of pregnancy-related mortality and severe maternal morbidity than women of other racial and ethnic groups (Figures 3 and 4).
FIGURE 3
Pregnancy-related mortality ratios by race and ethnicity – Pregnancy Mortality Surveillance System, U.S., 2007–2016.
PREGNANCY-RELATED MORTALITY RATIO
Pregnancy-related deaths per 100,000 live births
SMM also varies among different racial and ethnic groups. In 2017, the rates of SMM among hospital deliveries for non-hispanic black and AI/AN women were more than 1.5 times as high as those for white, Hispanic, Asian/Pacific Islander and women of other races and ethnicities (Figure 4).
EDUCATION
Women with at least some college education have lower pregnancy-related mortality ratios than those with a high school education or less (Figure 5). Black and AI/AN women have the highest pregnancy-related mortality ratios regardless of education level.
GEOGRAPHY
Maternal health outcomes have also been shown to vary by geographic location. During the period from 2007 to 2016, the pregnancy-related mortality ratio in the state with the highest ratio was 3.8 times that of the state with the lowest ratio.19 When states are grouped into high, medium, and low pregnancy-related mortality ratio categories, differences in pregnancy-related mortality by race and ethnicity persist. Black and AI/AN women have pregnancy-related mortality ratios approximately 2–3 times that of white women regardless of whether the group of states is in the high, medium or low category.20
Some states report higher rates of SMM (not including those who only received a blood transfusion) than others (Figure 6).4
FIGURE 6
Rate of SMM (per 10,000 delivery hospitalizations) by State, 2017. Note: States colored gray indicate that HCUP data were not available in 2017. Estimates do not include blood transfusions as an SMM indicator using ICD-10-CM/PCS in 2017.
MATERNAL AGE
Pregnancy-related deaths vary by maternal age, with the highest pregnancy-related mortality ratios reported for women aged 35 years and older.20 There are also racial and ethnic disparities in pregnancy-related deaths that increase by age. These are especially marked for black and AI/AN women (Figure 7).
SMM rates also vary by age. Women age 35 years and older also have a substantially higher rate of SMM than women in other groups at approximately 107 events per 10,000 delivery hospitalizations as compared to rates of approximately 60–70 events per 10,000 delivery hospitalizations in younger age groups (Figure 8).
FIGURE 8
Severe maternal morbidity (SMM) rate by age, 2017.
CONTRIBUTING FACTORS
Thirteen Maternal Mortality Review Committees (MMRCs) identified several factors that may contribute to pregnancy-related deaths, including those at the patient or family (e.g., lack of knowledge of warning signs), community (e.g., unstable housing), provider (e.g., lack of continuity of care), health facility (e.g., limited experience with obstetric emergencies), and system levels (e.g., lack of guiding policies, procedures, or standards).8
Similar factors may also contribute to maternal health disparities. One U.S. study found that site of care is a contributing factor to maternal health disparities such that hospitals with a higher proportion of deliveries to black women had higher rates of SMM for both black and white women than those with lower proportions of deliveries to black women, even after adjustment for selected patient and hospital characteristics.21
Conditions in which people are born, live, work and age, such as access to healthy food options, safe public spaces, and educational and employment opportunities, can also influence health.22 One conceptual model highlights these social determinants of health and suggests that patient factors, community or neighborhood factors, health care provider factors, and system factors also have a role in health outcomes.23 Further research is needed to determine how such factors influence maternal health outcomes and which ones have the most impact.
Footnotes
- 1
Administrative hospital discharge data with International Classification of Diseases (ICD) diagnosis and procedure codes are used to identify hospital deliveries with SMM. In October 2015, there was a transition from the 9th to 10th revision of the ICD coding system with a substantial increase in coding specificity for blood transfusions. Analyses are underway to better understand the impact of this coding change on blood transfusions, but preliminary data indicate significant decreases in reporting.
- 2
The SMM estimate is based on the Agency for Healthcare Research and Quality, Healthcare Cost and Utilization Project (HCUP), State Inpatient Databases (SID), 47 States and the District of Columbia (from all states except Alabama, Idaho, and New Hampshire), 2017 pooled estimates with ICD-10-CM/PCS coding. www
.hcup-us.ahrq.gov/sidoverview.jsp. HCUP SID Partners: https://www .hcup-us.ahrq .gov/partners.jsp?SID - 3
The SMM estimate is based on the Agency for Healthcare Research and Quality, Healthcare Cost and Utilization Project (HCUP), State Inpatient Databases (SID), 47 States and the District of Columbia (from all states except Alabama, Idaho, and New Hampshire), 2017 pooled estimates with ICD-10-CM/PCS coding. www
.hcup-us.ahrq.gov/sidoverview.jsp. HCUP SID Partners: https://www .hcup-us.ahrq .gov/partners.jsp?SID - 4
The SMM estimates are based on the Agency for Healthcare Research and Quality, Healthcare Cost and Utilization Project (HCUP), State Inpatient Databases (SID), 47 States and the District of Columbia (from all states except Alabama, Idaho, and New Hampshire), 2017 pooled estimates with ICD-10-CM/PCS coding. www
.hcup-us.ahrq.gov/sidoverview.jsp. HCUP SID Partners: https://www .hcup-us.ahrq .gov/partners.jsp?SID
- THE CURRENT STATE: MATERNAL MORTALITY AND MORBIDITY IN THE UNITED STATES - The S...THE CURRENT STATE: MATERNAL MORTALITY AND MORBIDITY IN THE UNITED STATES - The Surgeon General’s Call to Action to Improve Maternal Health
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