In 2017, overall maternal mortality rate in the US was 19/100,000 deliveries, as estimated by the WHO; incidence is 3 to 4 times higher in nonwhite women. Almost 50% of pregnancy-associated deaths in the US occur in non-Hispanic black women. The maternal mortality rate is higher in the US than in other Western countries (eg, Germany, Netherlands, Poland, Spain, Sweden, Switzerland, United Kingdom).
Maternal mortality ratios in selected countries
| Maternal mortality ratio refers to the number of women who die from pregnancy-related causes during pregnancy or within 42 days of the end of the pregnancy per 100,000 live births. In 2017, ratios ranged from 2 (Poland) to 1150 (South Sudan) per 100,000 live births (countries not shown). The maternal mortality ratio is higher in the US than in other Western countries.  Data from the World Health Organization, United Nations Children’s Fund (UNICEF), United Nations Population Fund (UNFPA), The World Bank, and the United Nations Population Division. Trends in Estimates of Maternal Mortality Ratio (MMR; Maternal Deaths per 100,000 Live Births) 2000–2017. Geneva, World Health Organization, 2019. |
Disparities by race and ethnicity in maternal mortality are significant worldwide. In the US, the maternal mortality rate is 3.3 times higher in black women and 2.5 times higher in American Indian and Alaska native women than in white women (1 References In a high-risk (at-risk) pregnancy, the mother, fetus, or neonate is at increased risk of morbidity or mortality before, during, or after delivery. In 2017, overall maternal mortality rate in... read more ). In Brazil, the maternal mortality is about 5 times higher in women of African descent than in white women; in the United Kingdom, it is higher in black women than in white women (2 References In a high-risk (at-risk) pregnancy, the mother, fetus, or neonate is at increased risk of morbidity or mortality before, during, or after delivery. In 2017, overall maternal mortality rate in... read more ).
Maternal death statistics include direct obstetric and indirect causes (3 References In a high-risk (at-risk) pregnancy, the mother, fetus, or neonate is at increased risk of morbidity or mortality before, during, or after delivery. In 2017, overall maternal mortality rate in... read more ).
The most common causes of maternal death worldwide are
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Abortion, including induced abortion Induced Abortion In the US, abortion of a previable fetus is legal, although state-specific restrictions (eg, mandatory waiting periods, gestational age restrictions) exist. In the US, about half of pregnancies... read more , miscarriage Spontaneous Abortion Spontaneous abortion is noninduced embryonic or fetal death or passage of products of conception before 20 weeks gestation. Threatened abortion is vaginal bleeding without cervical dilation... read more , and ectopic pregnancy Ectopic Pregnancy In ectopic pregnancy, implantation occurs in a site other than the endometrial lining of the uterine cavity—ie, in the fallopian tube, uterine cornua, cervix, ovary, or abdominal or pelvic cavity... read more ( ≥ 8%)
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Other disorders (eg, preexisting disorders such as obesity Obesity Obesity is excess body weight, defined as a body mass index (BMI) of ≥ 30 kg/m2. Complications include cardiovascular disorders (particularly in people with excess abdominal fat), diabetes mellitus... read more , operative delivery, and infectious diseases (eg, HIV infection Pulmonary Embolism (PE) Pulmonary embolism (PE) is the occlusion of pulmonary arteries by thrombi that originate elsewhere, typically in the large veins of the legs or pelvis. Risk factors for pulmonary embolism are... read more
)
Usually, several factors contribute to maternal mortality (4 References In a high-risk (at-risk) pregnancy, the mother, fetus, or neonate is at increased risk of morbidity or mortality before, during, or after delivery. In 2017, overall maternal mortality rate in... read more ). They include
About 3 of 5 maternal deaths are preventable (1 References In a high-risk (at-risk) pregnancy, the mother, fetus, or neonate is at increased risk of morbidity or mortality before, during, or after delivery. In 2017, overall maternal mortality rate in... read more ).
Perinatal mortality rate in offspring in the US is about 6 to 7/1000 deliveries; deaths are divided about equally between those during the late fetal period (gestational age > 28 weeks) and those during the early neonatal period (< 7 days after birth).
The most common causes of perinatal death are
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Maternal disorders (eg, hypertension Hypertension in Pregnancy Recommendations regarding classification, diagnosis, and management of hypertensive disorders (including preeclampsia) are available from the American College of Obstetricians and Gynecologists... read more , diabetes mellitus Diabetes Mellitus in Pregnancy Pregnancy aggravates preexisting type 1 (insulin-dependent) and type 2 (non–insulin-dependent) diabetes but does not appear to exacerbate diabetic retinopathy, nephropathy, or neuropathy (1)... read more , obesity Maternal Weight Risk factors for complications during pregnancy include Preexisting maternal disorders Physical and social characteristics (eg, age) Problems in previous pregnancies (eg, spontaneous abortions)... read more
, autoimmune disorders Autoimmune Disorders in Pregnancy Autoimmune disorders are 5 times more common among women, and incidence tends to peak during reproductive years. Thus, these disorders commonly occur in pregnant women. Antiphospholipid antibody... read more ) -
Infection
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Genetic abnormalities in the fetus
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Congenital malformations
Other maternal characteristics that increase the risk of perinatal mortality include maternal age (much younger or older than average), unmarried status, smoking, and multiple gestations.
References
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1. Petersen EE, Nicole L. Davis NL, Goodman D, et al: Vital Signs: Pregnancy-related deaths, United States, 2011–2015, and strategies for prevention, 13 states, 2013–2017. MMWR Morb Mortal Wkly Rep 68 (18): 423–429, 2019. doi: 10.15585/mmwr.mm6818e1
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2. Small M, Allen T, Brown HL: Global disparities in maternal morbidity and mortality. Semin Perinatol 41 (5): 318–322, 2017. doi: 10.1053/j.semperi.2017.04.009
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3. Say L, Chou D, Gemmill A, et al: Global causes of maternal death: A WHO systematic analysis. Lancet Glob Health 2 (6) :e323–33, 2014. doi: 10.1016/S2214-109X(14)70227-X
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4. Building U.S. Capacity to Review and Prevent Maternal Deaths: Report from Nine Maternal Mortality Review Committees.
Risk Assessment During Pregnancy
Risk assessment is part of routine prenatal care. Family history and genetic evaluation Genetic Evaluation Genetic evaluation is part of routine prenatal care and is ideally done before conception. The extent of genetic evaluation a woman chooses is related to how the woman weighs factors such as... read more 
are especially important. Risk is also assessed during or shortly after labor and at any time that events may modify risk status. Risk factors Risk Factors for Complications During Pregnancy Risk factors for complications during pregnancy include Preexisting maternal disorders Physical and social characteristics (eg, age) Problems in previous pregnancies (eg, spontaneous abortions)... read more are assessed systematically because each risk factor present increases overall risk.
Several pregnancy monitoring and risk assessment systems are available. The most widely used system is the Pregnancy Assessment Monitoring System ( PRAMS), which is a project of the Centers for Disease Control and Prevention (CDC) and state health departments. PRAMS provides information for state health departments to use to improve the health of mothers and infants. PRAMS also enables the CDC and states to monitor changes in health indicators (eg, unintended pregnancy, prenatal care, breastfeeding, smoking, drinking, infant health).
High-risk pregnancies require close monitoring and sometimes referral to a perinatal center, especially if women have complex high-risk conditions. These centers offer many specialty and subspecialty services, provided by maternal, fetal, and neonatal specialists (1 Risk assessment reference In a high-risk (at-risk) pregnancy, the mother, fetus, or neonate is at increased risk of morbidity or mortality before, during, or after delivery. In 2017, overall maternal mortality rate in... read more ). When referral is needed, transfer before rather than after delivery results in lower neonatal morbidity and mortality rates.
The most common reasons for referral before delivery are
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Preexisting or developing disorders (eg, diabetes Diabetes Mellitus (DM) Diabetes mellitus is impaired insulin secretion and variable degrees of peripheral insulin resistance leading to hyperglycemia. Early symptoms are related to hyperglycemia and include polydipsia... read more , hypertension Hypertension Hypertension is sustained elevation of resting systolic blood pressure (≥ 130 mm Hg), diastolic blood pressure (≥ 80 mm Hg), or both. Hypertension with no known cause (primary; formerly, essential... read more
, severe [morbid] obesity Obesity Obesity is excess body weight, defined as a body mass index (BMI) of ≥ 30 kg/m2. Complications include cardiovascular disorders (particularly in people with excess abdominal fat), diabetes mellitus... read more )
Risk assessment reference
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1. American College of Obstetricians and Gynecologists: Levels of maternal care: Obstetric care consensus No. 9. Obstet Gynecol 134(2):428-434, 2019. doi: 10.1097/AOG.0000000000003384
