Abstract
This chapter reviews the epidemiology and etiologies of maternal mortality, focusing first on low-income countries, which account for 99% of maternal deaths worldwide. The chapter next addresses maternal mortality in high-income countries, and highlights the increasing maternal mortality ratio in the United States. Maternal morbidity is next presented as a measure of serious injury that is sufficiently frequent to support quality improvement efforts that may decrease the risk of both morbidity and death. Finally, epidemiology and mechanisms of anesthesia-related maternal mortality are discussed, along with recommendations for practice to ensure maternal safety.
Keywords
Maternal mortality, Direct death, Indirect death, Pregnancy-associated mortality, Pregnancy-related mortality, Anesthesia-related mortality, Severe maternal morbidity
Global Maternal Mortality
Globally in 2015, an estimated 303,000 women died while pregnant or within 42 days of the end of pregnancy. This number corresponds to a ratio of 216 maternal deaths per 100,000 live births and to a 1-in-180 lifetime risk for pregnancy-related death for each girl entering her childbearing years ( Table 39.1 ). According to the World Health Organization (WHO), “No issue is more central to global well-being than maternal and perinatal health. Every individual, every family and every community is at some point intimately involved in pregnancy and the success of childbirth.”
| Region | MMR | RANGE OF MMR UNCERTAINTY | Number of Maternal Deaths a | Lifetime Risk for Maternal Death, a 1 in: | |
|---|---|---|---|---|---|
| Lower Estimate | Upper Estimate | ||||
| World | 215 | 207 | 249 | 303,000 | 180 |
| Developed Regions b | 12 | 11 | 14 | 1700 | 4900 |
| Developing Regions | 239 | 229 | 275 | 302,000 | 150 |
| Northern Africa c | 70 | 56 | 92 | 3100 | 450 |
| Sub-Saharan Africa d | 546 | 511 | 652 | 201,000 | 36 |
| Eastern Asia e | 27 | 23 | 33 | 4800 | 2300 |
| Southern Asia f | 176 | 153 | 216 | 66,000 | 210 |
| Southeastern Asia g | 110 | 95 | 142 | 13,000 | 380 |
| Western Asia h | 91 | 73 | 125 | 4700 | 360 |
| Caucasus and Central Asia i | 33 | 27 | 45 | 610 | 1100 |
| Latin America j | 60 | 57 | 66 | 6600 | 760 |
| Caribbean k | 175 | 130 | 265 | 1300 | 250 |
| Oceania l | 187 | 95 | 381 | 500 | 150 |
a Numbers of maternal deaths and lifetime risk numbers have been rounded according to the following scheme: < 100 rounded to nearest 1; 100–999 rounded to nearest 10; 1000–9999 rounded to nearest 100; and ≥ 10,000 rounded to nearest 1000.
b Albania, Australia, Austria, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, Canada, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Israel, Italy, Japan, Latvia, Lithuania, Luxembourg, Malta, Montenegro, Netherlands, New Zealand, Norway, Poland, Portugal, Republic of Moldova, Romania, Russian Federation, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, the former Yugoslav Republic of Macedonia, Ukraine, United Kingdom, and the United States of America.
c Algeria, Egypt, Libya, Morocco, Tunisia.
d Angola, Benin, Botswana, Burkina Faso, Burundi, Cameroon, Cabo Verde, Central African Republic, Chad, Comoros, Congo, Côte d’Ivoire, Democratic Republic of the Congo, Djibouti, Equatorial Guinea, Eritrea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Lesotho, Liberia, Madagascar, Malawi, Mali, Mauritania, Mauritius, Mozambique, Namibia, Niger, Nigeria, Rwanda, Sao Tome and Principe, Senegal, Seychelles, Sierra Leone, Somalia, South Africa, Sudan, South Sudan, Swaziland, Togo, Uganda, United Republic of Tanzania, Zambia, Zimbabwe.
e China, Democratic People’s Republic of Korea, Mongolia, Republic of Korea.
f Afghanistan, Bangladesh, Bhutan, India, Iran (Islamic Republic of), Maldives, Nepal, Pakistan, Sri Lanka.
g Brunei Darussalam, Cambodia, Indonesia, Lao People’s Republic, Malaysia, Myanmar, Philippines, Singapore, Thailand, Timor-Leste, Viet Nam.
h Bahrain, Iraq, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syrian Arab Republic, Turkey, United Arab Emirates, West Bank and Gaza Strip territory (the State of Palestine), Yemen.
i Armenia, Azerbaijan, Georgia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan.
j Argentina, Belize, Bolivia (Plurinational State of), Brazil, Chile, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, Uruguay, Venezuela (Bolivarian Republic of).
k Bahamas, Barbados, Cuba, Dominican Republic, Grenada, Haiti, Jamaica, Puerto Rico, Saint Lucia, Saint Vincent and the Grenadines, Trinidad and Tobago.
l Fiji, Kiribati, Micronesia (Federated States of), Papua New Guinea, Samoa, Solomon Islands, Tonga, Vanuatu.
Definitions for maternal death are listed in Table 39.2 , and measures of maternal mortality are listed in Table 39.3 . More than 99% of maternal deaths occur in low- and middle-income countries, with 84% in either sub-Saharan Africa or South Asia ( Fig. 39.1 ). Between 1990 and 2015, the global maternal mortality ratio (MMR) fell by 44%, an impressive improvement, but less than the 75% reduction targeted by the Millennium Development Goals. In 2015, the United Nations issued 17 Sustainable Development Goals, including a commitment to reduce the global MMR to less than 70 per 100,000 live births by 2030, with no single country having an MMR of more than 140. Several regions will require substantial investment to meet this goal, most notably sub-Saharan Africa, where the lifetime risk for maternal death remains remarkably high, at 1 in 36. There is considerable regional variation. Within sub-Saharan Africa, the highest MMRs are in Sierra Leone (1360), Central African Republic (882), and Chad (856) and represent rates that are 10-fold higher than the lowest ratios in the region. Throughout the world, war, natural disaster, and political conflict can degrade health systems and trigger a rise in deaths caused by complications that would be treatable under stable conditions.
| Source | Term | Definition a |
|---|---|---|
| World Health Organization | Maternal death | Death while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from accidental or incidental causes. ICD-10 A34, O00-O95, O98-O99 b |
| Direct maternal death | Death resulting from obstetric complications of the pregnant state (pregnancy, labor, and the puerperium), from interventions, omissions, incorrect treatment, or from a chain of events resulting from any of the above. A34, O00-O95 b | |
| Indirect maternal death | Death resulting from previous existing disease or disease that developed during pregnancy and that was not a result of direct obstetric causes but was aggravated by physiologic effects of pregnancy. O98-O99 b | |
| Late maternal death | Death of a woman from direct or indirect obstetric causes more than 42 days but less than 1 year after termination of pregnancy. O96-O97 b | |
| U.S. Centers for Disease Control and Prevention, Pregnancy Mortality Surveillance System c | Pregnancy-associated death | Death while pregnant or within 1 year of termination of pregnancy, irrespective of cause. |
| Pregnancy-related death | Death while pregnant or within 1 year of termination of pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes. | |
| Non–pregnancy-related death | Death while pregnant or within 1 year of termination of pregnancy, from a cause unrelated to pregnancy. |
a Numbers after some definitions indicate cause of death codes.
b ICD-10, International Statistical Classification of Diseases and Related Health Problems: 10th revision.
c From Berg CJ, Callaghan WM, Syverson C, Henderson Z. Pregnancy-related mortality in the United States, 1998 to 2005. Obstet Gynecol. 2010;116:1302–1309.
| Maternal Mortality Measure | Definitions | Reports Using the Measure |
|---|---|---|
| Maternal mortality ratio (MMR) | Direct and indirect maternal deaths, but not late maternal deaths, per 100,000 live births | WHO |
| Maternal mortality rate | Direct and indirect maternal deaths, but not late maternal deaths, per 100,000 maternities (pregnancies resulting in a live birth or stillbirth ≥ 20 weeks gestational age) | UK CEMD |
| Pregnancy-related mortality ratio (PRMR) | Pregnancy-related deaths per 100,000 live births | U.S. CDC PMSS 172 |
| Lifetime risk for maternal death | The lifetime risk for maternal death takes into account both the probability of becoming pregnant and the probability of dying as a result of that pregnancy cumulated across a woman’s reproductive years | WHO |
Leading Causes
Hemorrhage, hypertensive disorders of pregnancy, and sepsis account for more than one-half of global maternal deaths and for slightly more than one-third of deaths in the developed world. Hemorrhage is the leading direct cause of maternal death worldwide, followed by hypertensive disorders, causing an estimated 27.1% and 14.0% of all deaths, respectively (see Fig. 39.1 ). Infection and sepsis may be substantially underestimated in regions where laboratory diagnostic tests are unavailable. In one Malawi hospital with full laboratory capabilities, infection played a primary role in almost three-fourths of all maternal deaths.
Rarely, anemia can cause lethal congestive heart failure in pregnancy, but more commonly, it increases the risk for maternal death from other complications, particularly hemorrhage and infection. Risk factors associated with anemia include (1) iron and other micronutrient deficiencies, (2) pregnancy intervals of less than 1 year, (3) adolescent pregnancy, (4) hemoglobinopathy, (5) urinary tract infection, (6) human immunodeficiency virus (HIV) infection, (7) parasitic infections including malaria, and (8) recurrent antepartum hemorrhage.
Obstructed labor causes less than 10% of maternal deaths worldwide, but it is an important cause of mortality in communities where early adolescent pregnancy is common, childhood malnutrition leads to small maternal pelvices, and operative delivery is unavailable. Death from obstructed labor is largely the result of hemorrhage caused by uterine rupture, or sepsis caused by ascending genital tract infection, and deaths may be coded under those categories. Prolonged pressure on the pelvic outlet can lead to tissue necrosis and obstetric fistula, which is thought to affect between 2 and 3.5 million women worldwide.
HIV/acquired immune deficiency syndrome (AIDS) increases vulnerability to both nonobstetric infection (e.g., tuberculosis, malaria) and obstetric complications (e.g., hemorrhage, pregnancy-related sepsis, septic abortion). Global mortality attributed to HIV/AIDS peaked in 2004, and the WHO attributed 1.6% of maternal deaths in 2015 to HIV/AIDS. In countries most severely affected (e.g., Botswana, Malawi, South Africa), MMRs increased between 1990 and 2000, but they have subsequently declined with increasing availability of antiretroviral therapy.
Maternal deaths attributed to unsafe abortion account for 5% to 13% of maternal deaths worldwide. The WHO defines unsafe abortion as “a procedure for terminating an unintended pregnancy either by individuals without the necessary skills or in an environment that does not conform to minimum medical standards, or both.” Worldwide, 45% of abortions were unsafe between 2010 and 2014, compared with 44% in 1995. The case-fatality rate (460 maternal deaths per 100,000 unsafe abortions) and the absolute number of maternal deaths per year (28,500) are highest in sub-Saharan Africa.
Early marriage (before 18 years of age) has been identified as a major health risk for girls, increasing their exposure to domestic violence, coercion, pregnancy, and sexually transmitted diseases such as HIV/AIDS. Girls younger than 15 years of age are four times more likely to die in childbirth than women in their 20s, and pregnancy is among the leading causes of death worldwide for girls 15 to 19 years of age. Early childbearing also increases the likelihood of high parity birth (greater than or equal to 5) later in life. With a threefold increase in the MMR, high parity is the most important demographic risk for maternal death because it remains so common, accounting for 29% of births globally between 1990 and 2005. Advanced maternal age is less common globally, but the MMR increases threefold by 35 years, sevenfold by 40 years, and 15-fold after 45 years of age.
Anesthesia providers working in the developing world must contend with profound limitations in staffing, equipment, and other resources. In addition, patients who labor at home may face a variety of social and environmental obstacles to reach a facility with the capacity to provide comprehensive emergency obstetric care, and many arrive at these facilities in septic or hemorrhagic shock. Cesarean delivery is the most common major surgical procedure in Africa. Perioperative maternal mortality is estimated to be between 1.2% and 2%, with one in seven deaths associated with cesarean delivery attributed to anesthesia. Although general anesthesia is associated with a threefold increased risk for death (5.9 per 1000 general anesthetics versus 1.2 per 1000 neuraxial anesthetics), reports of high spinal anesthesia and hemodynamic collapse highlight potential hazards with neuraxial anesthesia. Failed airway management (including bronchospasm and aspiration of gastric contents) accounts for three-fourths of anesthesia-related deaths reported from low- and middle-income countries. Peripartum deaths have also been attributed to limited availability or affordability of blood products, cardiac arrest at induction of anesthesia, drug overdose, adverse medication reaction, and drug error. The number of maternal perioperative deaths likely pales in comparison with maternal deaths that result from the unmet need for lifesaving obstetric procedures, including cesarean delivery.
Strategies to reduce global maternal mortality include (1) improvement in family planning services and a reduction in the performance of unsafe abortion ; (2) community-based education focused on safe birth practices and indications for transfer to a higher level of care ; and (3) development of the infrastructure needed to provide timely emergency obstetric care, including the performance of indicated cesarean delivery (and safe administration of anesthesia) by trained care providers, who can also provide resuscitation of women in whom shock develops secondary to hemorrhage or infection. Cluster randomized trials and cost-effectiveness analyses to evaluate these strategies are beginning to appear. When deployed as part of an integrated, context-specific, and culturally sensitive program, interventions to reduce maternal and fetal mortality can be highly cost effective.
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