Maternal Mortality -- United States, 1982-1996

Maternal and infant mortality are basic health indicators that reflect a nation's health status. In the United States, infant mortality has declined steadily; however, this is not true for maternal mortality. This report presents data from death certificates compiled by CDC's National Center for Health Statistics, which indicate that in the United States, the annual maternal mortality ratio * remained approximately 7.5 maternal deaths per 100,000 live births during 1982-1996.

Annual maternal mortality ratios were calculated using information contained on death certificates filed in state vital statistics offices and compiled by CDC (1,2). Maternal deaths were defined as those deaths that occurred during a pregnancy or within 42 days of the end of a pregnancy and for which the cause of death was listed as a complication of pregnancy, childbirth, or the puerperium (International Classification of Diseases, Ninth Revision, codes 630-676). Maternal mortality ratios were calculated as the number of maternal deaths per 100,000 live births (1,2).

In 1930, the national maternal mortality ratio was 670 maternal deaths per 100,000 live births (3). The ratio declined substantially during the 1940s and 1950s, and continued to decline until 1982. During 1982-1996, the annual maternal mortality ratio fluctuated between approximately 7 and 8 maternal deaths per 100,000 live births (Figure_1). During that time, trends by race were similar to the overall ratio, and no reductions were observed for either black or white women. Maternal mortality ratios remained higher for black women than for white women. Ratios for black women generally fluctuated between 18 and 22 per 100,000 births and for white women between 5 and 6 per 100,000 live births.

Reported by: Div of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion; Div of Vital Statistics, National Center for Health Statistics, CDC.

Editorial Note

Editorial Note: Since 1982 in the United States, no progress has been made toward achieving the Healthy People 2000 goal of 3.3 maternal deaths per 100,000 live births set in 1987 (objective 14.3) (4). The reason for this lack of improvement in maternal mortality is not clear. However, during this same time period, infant mortality has declined steadily because of advances in the survival of low birthweight and preterm infants and in the prevention of some causes of postneonatal mortality, such as sudden infant death syndrome.

The United States has not reached an irreducible minimum in maternal mortality; WHO estimates demonstrate that 20 countries have reduced maternal mortality levels to below those of the United States (5). Primary prevention of maternal deaths, such as those associated with ectopic pregnancy and some cases of infection and hemorrhage, is possible. However, some complications that can occur during pregnancy cannot be prevented (e.g., pregnancy-induced hypertension, placenta previa, retained placenta, and thromboembolism). Nevertheless, more than half of all maternal deaths can be prevented through early diagnosis and appropriate medical care of pregnancy complications (6,7). Hemorrhage, pregnancy-induced hypertension, infection, and ectopic pregnancy continue to account for most (59%) maternal deaths.

When compared with white women, black women continue to have four times the risk for dying from complications of pregnancy and childbirth (2), although the risk for developing maternal complications is less than twice that of white women (8). This suggests that access to and use of health-care services for early diagnosis and effective treatment, if complications develop, may be a factor. In 1996, if the maternal mortality ratio for black women were equal to that for white women, the national maternal mortality ratio would have declined by 32% from 7.6 to 5.1 per 100,000 live births.

In this report, maternal mortality ratios are based solely on vital statistics data and are underestimates because of misclassification. The number of deaths attributed to pregnancy and its complications is estimated to be 1.3 to three times that reported in vital statistics records (6). Misclassification of maternal deaths occurs when the cause of death on the death certificate does not reflect the relation between a woman's pregnancy and her death. In addition, the inclusion of deaths causally related to pregnancy that occur between 43 and 365 days postpregnancy can increase the number of maternal deaths identified by 5%-10% (6).

To identify interventions that may have an impact on reducing maternal mortality, approximately 25 states have reestablished maternal mortality review committees. These committees review various factors that may have contributed to maternal deaths, including the quality of medical care and systemic problems in the health-care delivery system. To assess the problem and develop appropriate interventions to reduce the number of maternal deaths, all states should implement active surveillance of maternal mortality, including maternal mortality review committees.

In 1998, the World Health Organization designated Safe Motherhood as the focus for World Health Day (April 7), indicating the importance of this issue globally. In the United States, several measures that need to be implemented include providing all women with access to family planning services, because unintended pregnancies are associated with higher risks for both mother and infant (9). Women should know how to prevent sexually transmitted diseases (STDs), and women with STDs need effective and early treatment to prevent ectopic pregnancies. All women need access to culturally appropriate and quality prenatal, delivery, and postpartum care. The prevention of complications and the early diagnosis and effective treatment of any complication is critical. Although prenatal-care use in the United States has been increasing, in 1996, approximately 10% of all pregnant women received inadequate or no prenatal care (10).

In the United States, the theme for World Health Day 1998 was "Invest in the Future: Support Safe Motherhood." The proposed Healthy People 2010 goal for maternal mortality remains 3.3 maternal deaths per 100,000 live births. Unless investments are made in improving maternal health for all women, this goal will not be reached.

References

1. National Center for Health Statistics. Vital statistics of the United States. Vol II -- mortality. Part A. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1967-1992.

2. National Center for Health Statistics. Health, United States, 1998, with socioeconomic status and health chartbook. Hyattsville, Maryland: US Department of Health and Human Services, 1998; DHHS publication no. (PHS)98-1232.

3. Linder FE, Grove RD. Vital statistics ratios in the United States, 1900-1940. Washington, DC: US Department of Commerce, Bureau of the Census, 1943.

4. Public Health Service. Healthy people 2000: national health promotion and disease prevention objectives -- full report, with commentary. Washington, DC: US Department of Health and Human Services, Public Health Service, 1991; DHHS publication no. (PHS)91-50212.

5. World Health Organization. WHO revised 1990 estimates of maternal mortality: a new approach by WHO and UNICEF. Geneva, Switzerland: World Health Organization, 1996; report no. WHO/FRH/MSM/96.11.

6. Berg CJ, Atrash HK, Koonin LM, et al. Pregnancy-related mortality in the United States, 1987-1990. Obstet Gynecol 1996;88:161-7.

7. Mertz KJ, Parker AL, Halpin GJ. Pregnancy-related mortality in New Jersey, 1975-1989. Am J Public Health 1992;82:1085-8.

8. Bennett TA, Kotelchuck M, Cox CE, et al. Pregnancy-associated hospitalizations in the United States in 1991 and 1992: a comprehensive view of maternal morbidity. Am J Obstet Gynecol 1998;178:346-54.

9. Brown SS, Eisenberg L, eds. The best intentions: unintended pregnancy and the well-being of children and families. Washington, DC: National Academy Press, 1995.

10. National Center for Health Statistics. Report of final natality statistics, 1996. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1998; DHHS publication no. (PHS)98-1120. (Monthly vital statistics report; vol. 46, no. 11, suppl).

CDC's National Center for Health Statistics uses the term maternal mortality rate. In this report, the term "ratio" is used instead of rate because the numerator includes some maternal deaths that were not related to live births and thus were not included in the denominator.

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