Current Trends Infant Mortality -- United States, 1992

The final infant mortality (death before age 1 year) rate for the United States for 1992 -- 8.5 infant deaths per 1000 live-born infants -- was the lowest rate ever recorded and represented a decrease of 4.5% from the rate of 8.9 for 1991 Figure_1. Based on provisional data, the trend in declining infant mortality continued through 1993 (rate: 8.3) (1). This report characterizes infant mortality in 1992 using information from birth and death certificates compiled by CDC's National Center for Health Statistics (2) and compares findings with those for 1991.

In this report, cause-of-death statistics are based on the underlying cause of death * reported on the death certificate by the attending physician, medical examiner, or coroner in a manner specified by the World Health Organization. Because race reflects differing distributions of several risk factors for infant death (e.g., low birthweight {LBW} { less than 2500 g (5 lbs 9 oz) at birth}) and is useful for identifying groups at greatest risk for infant death, this analysis examines race-specific mortality rates. Race for infant deaths was tabulated by race of decedent; race for live-born infants (who comprise the denominators of infant mortality rates) was tabulated by race of mother. Rates are presented only for black and white infants because the Linked Birth/Infant Death Data Set (used to more accurately estimate infant mortality rates for other racial groups) was not available for 1991 and 1992.

In 1992, a total of 34,628 infants died, compared with 36,766 in 1991. The mortality rate for white ** infants in 1992 (6.9 per 1000) decreased 5.5% from the rate in 1991 (7.3), while the rate for black ** infants in 1992 (16.8) decreased 4.5% from 1991 (17.6). From 1991 through 1992, the overall neonatal mortality (death before age 28 days) rate decreased 3.6% (5.6 to 5.4 per 1000); for white infants, the rate decreased from 4.5 to 4.3 and for black infants, from 11.2 to 10.8. The overall postneonatal mortality (death at age 28 days-11 months) rate decreased 8.8% (3.4 to 3.1 per 1000); for white infants, the rate decreased from 2.8 to 2.6, and for black infants, from 6.3 to 6.0.

From 1991 to 1992, the infant mortality rate decreased for six of the 10 leading causes of infant death and increased for three causes Table_1. The largest decreases were for respiratory distress syndrome (RDS) (18.7%), accidents *** and adverse effects (14.1%), and sudden infant death syndrome (SIDS) (7.5%). Increases occurred for the categories of newborn affected by complications of placenta, cord, and membranes (4.3%); infections specific to the perinatal period (3.7%); and intrauterine hypoxia and birth asphyxia (3.4%).

The rank order of the 10 leading causes of infant death differed by race Table_1. Although the first four leading causes of death were the same for white and black infants, their rank ordering differed; these same four causes accounted for 54.8% and 50.0% of all deaths among white and black infants, respectively. For white infants, the leading cause of death was congenital anomalies (25.6%); for black infants, the leading cause of death was disorders relating to short gestation and unspecified LBW (17.8%).

In 1992, the risk for death during the first year of life was 2.4 times greater for black than for white infants. For each of the leading causes of death, the risk for death was higher for black than for white infants, although there were large variations in the magnitude of the excess by cause. The cause-specific ratios were highest for disorders relating to short gestation and unspecified LBW (5.0:1), pneumonia and influenza (2.9:1), and RDS and infections specific to the perinatal period (2.5:1). The ratios were lowest for newborn affected by complications of placenta, cord, and membranes (2.1:1) and congenital anomalies (1.2:1). Reported by: Mortality Statistics Br, Div of Vital Statistics, National Center for Health Statistics, CDC.

Editorial Note

Editorial Note: The infant mortality rate -- a standard index of health -- is higher in the United States than in many other developed countries. In 1990 (the most recent year for which comparative data are available), the U.S. infant mortality rate ranked 24th among countries or geographic areas with a population of at least 1 million (3), a decline in rank from 1980 (20th) (4).

During the 1970s, the U.S. infant mortality rate declined 4.6% per year but slowed to an annual average decrease of 2.8% during the 1980s. From 1990 to 1991, the infant mortality rate declined 3.3%; approximately half of this decrease represented declines in mortality from congenital anomalies (34.6%) and RDS (18.5%). From 1991 to 1992, the infant mortality rate declined 4.5%; nearly half of this decrease represented declines in mortality from RDS (26.2%) and SIDS (21.9%).

Differences in infant mortality rates by race may reflect differences in factors such as socioeconomic status, access to medical care, and the prevalence of specific risks. For example, the mortality rate is substantially higher for infants born to mothers of low socioeconomic status (5). In 1990, nearly three times as many black as white infants (56% versus 20%) were members of families with incomes below the poverty level (Bureau of the Census, unpublished data, 1992). In addition, because of income differentials, a lower proportion of black women have health insurance that covers the costs of adequate care for pregnancy and childbirth (6).

LBW is an important intermediate variable between some risk factors and infant mortality. In 1988 (the most recent year for which such data were available), 6.9% of infants had LBW; however, 59.2% of all infant deaths occurred among these infants. In 1992, a total of 13.3% of black infants had LBW, compared with 5.8% of white infants (7). Most of the causes of death for which black infants are at substantially elevated risk are closely associated with LBW. For three of the four causes of infant death characterized by the highest ratios of black-to-white mortality rates (i.e., disorders relating to short gestation and unspecified LBW, RDS, and newborn affected by maternal complications of pregnancy), 91.4% of the deaths in 1988 occurred among LBW infants (CDC, unpublished data, 1994).

The 1990 national health objective to reduce the overall infant mortality rate to nine deaths per 1000 live-born infants (8) was achieved in 1991 (rate: 8.9). A year 2000 national health objective is to reduce the overall infant mortality rate to no more than seven per 1000 live-born infants (objective 14.1) (9). This objective can be achieved by sustaining an average annual decrease of at least 2.4% for the total population.

Strategies to achieve the national health objective for reducing infant mortality should consider the heterogeneity of factors accounting for infant mortality in the United States. For example, reducing mortality from disorders related to short gestation and unspecified LBW will require improved access to adequate prenatal care and understanding of etiologic risk factors for preterm delivery; reduction of deaths related to maternal complications of pregnancy will require both expansion of access to prenatal care and assessment of the adequacy of the content of care (10). Efforts to address these and other risk factors may increase the likelihood of achieving the year 2000 national health objective for infant mortality.

References

1. NCHS. Annual summary of births, marriages, divorces, and deaths: United States, 1993. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1994. (Monthly vital statistics report; vol 42, no. 13).

2. NCHS. Advance report of final mortality statistics, 1992. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1994. (Monthly vital statistics report; vol 43, no. 6, suppl).

3. NCHS. Health, United States, 1993. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1994; DHHS publication no. (PHS)94-1232.

4. NCHS. Health, United States, 1988. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1989; DHHS publication no. (PHS)89-1232.

5. Gould JB, Davey B, LeRoy S. Socioeconomic differentials and neonatal mortality: racial comparison of California singletons. Pediatrics 1989;83:181-6.

6. Alan Guttmacher Institute. Blessed events and the bottom line: financing maternity care in the United States. New York: Alan Guttmacher Institute, 1987.

7. NCHS. Advance report of final natality statistics, 1992. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1994. (Monthly vital statistics report; vol 43, no. 5, suppl).

8. Public Health Service. The 1990 health objectives for the nation: a midcourse review. Washington, DC: US Department of Health and Human Services, Public Health Service, 1986.

9. 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.

10. Public Health Service. Caring for our future: the content of prenatal care -- a report of the Public Health Service Expert Panel on the Content of Prenatal Care. Washington, DC: US Department of Health and Human Services, Public Health Service, 1989.

* Defined by the International Classification of Diseases, Ninth Revision, as "(a) the disease or injury which initiated the train of morbid events leading directly to death, or (b) the circumstances of the accident or violence which produced the fatal injury." 

** Includes both Hispanic and non-Hispanic infants. 

*** When a death occurs under "accidental" circumstances, the preferred term within the public health community is "unintentional injury."

TABLE 1. Number of infant deaths, mortality rate, * and percentage of deaths attributed to the 10
leading causes of death, by race + of mother and cause -- United States, 1992
====================================================================================================
Race/                                                                                   %
  Rank order & Cause of death (ICD-9 @ code)                     No.       Rate    Distribution
----------------------------------------------------------------------------------------------------
BLACK
  1          Disorders relating to short gestation
               and unspecified low birthweight (765)            2,025     300.6       17.8
  2          Congenital anomalies (740-759)                     1,477     219.3       13.0
  3          Sudden infant death syndrome (798.0)               1,471     218.4       13.0
  4          Respiratory distress syndrome (769)                  705     104.7        6.2
  5          Newborn affected by maternal complications
               of pregnancy (761)                                 466      69.2        4.1
  6          Infections specific to the perinatal period (771)    306      45.4        2.7
  7          Newborn affected by complications
               of placenta, cord, and membranes (762)             298      44.2        2.6
  8          Accidents ** and adverse effects (E800-E949)         251      37.3        2.2
  9          Pneumonia and influenza (480-487)                    216      32.1        1.9
 10          Intrauterine hypoxia and birth asphyxia (768)        185      27.5        1.6
             All other causes (residual)                        3,948     586.1       34.8
All causes                                                     11,348   1,684.6      100.0

WHITE
  1          Congenital anomalies (740-759)                     5,666     177.0       25.6
  2          Sudden infant death syndrome (798.0)               3,239     101.2       14.6
  3          Disorders relating to short gestation
               and unspecified low birthweight (765)            1,926      60.2        8.7
  4          Respiratory distress syndrome (769)                1,321      41.3        6.0
  5          Newborn affected by maternal complications
               of pregnancy (761)                                 963      30.1        4.3
  6          Newborn affected by complications
               of placenta, cord, and membranes (762)             659      20.6        3.0
  7          Infections specific to the perinatal period (771)    573      17.9        2.6
  8          Accidents ** and adverse effects (E800-E949)         533      16.6        2.4
  9          Intrauterine hypoxia and birth asphyxia (768)        404      12.6        1.8
 10          Pneumonia and influenza (480-487)                    357      11.2        1.6
             All other causes (residual)                        6,523     203.7       29.4
All causes                                                     22,164     692.3      100.0

TOTAL ++

  1          Congenital anomalies (740-759)                     7,449     183.2       21.5
  2          Sudden infant death syndrome (798.0)               4,891     120.3       14.1
  3          Disorders relating to short gestation
               and unspecified low birthweight (765)            4,035      99.3       11.7
  4          Respiratory distress syndrome (769)                2,063      50.8        6.0
  5          Newborn affected by maternal complications
               of pregnancy (761)                               1,461      35.9        4.2
  6          Newborn affected by complications
               of placenta, cord, and membranes (762)             993      24.4
  7          Infections specific to the perinatal period (771)    901      22.2        2.6
  8          Accidents ** and adverse effects (E800-E949)         819      20.1        2.4
  9          Intrauterine hypoxia and birth asphyxia (768)        613      15.1        1.8
 10          Pneumonia and influenza (480-487)                    600      14.8        1.7
             All other causes (residual)                       10,803     265.8       31.2
All causes                                                     34,628     851.9      100.0
----------------------------------------------------------------------------------------------------
 * Death before age 1 year, per 100,000 live-born infants in specified group.
 + Hispanics and non-Hispanics are included in both racial groups. Race differences are given only
   for black and white infants because the Linked Birth/Infant Death Data Set (used to more
   accurately estimate infant mortality rates for other racial groups) was not available for 1992.
 & Based on number of deaths.
 @ International Classification of Diseases, Ninth Revision.
** When a death occurs under "accidental" circumstances, the preferred term within the public
   health community is "unintentional injury."
++ Includes races other than black and white.
====================================================================================================

Disclaimer   All MMWR HTML versions of articles are electronic conversions from ASCII text into HTML. This conversion may have resulted in character translation or format errors in the HTML version. Users should not rely on this HTML document, but are referred to the electronic PDF version and/or the original MMWR paper copy for the official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

Page converted: 09/19/98

HOME  |  ABOUT MMWR  |  MMWR SEARCH  |  DOWNLOADS  |  RSS |  CONTACT POLICY  |  DISCLAIMER  |  ACCESSIBILITY

Morbidity and Mortality Weekly Report Centers for Disease Control and Prevention 1600 Clifton Rd, MailStop E-90, Atlanta, GA 30333, U.S.A Department of Health and Human Services

This page last reviewed 5/2/01