Table 16Infant mortality rates, by birthweight: United States, selected years 1983–2006

[Data are based on linked birth and death certificates for infants]

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Birthweight1983119851199011995220002200422005220062
Infant deaths per 1,000 live births3
All birthweights10.910.48.97.66.96.86.96.7
Less than 2,500 grams95.993.978.165.360.257.957.655.7
 Less than 1,500 grams400.6387.7317.6270.7246.9245.2245.7241.4
  Less than 500 grams890.3895.9898.2904.9847.9850.1857.2847.6
  500–999 grams584.2559.2440.1351.0313.8314.6305.1303.8
  1,000–1,499 grams162.3145.497.969.660.955.758.158.4
 1,500–1,999 grams58.454.043.833.528.727.427.026.2
 2,000–2,499 grams22.520.917.813.711.911.110.910.4
2,500 grams or more4.74.33.73.02.52.32.32.3
 2,500–2,999 grams8.87.96.75.54.64.24.24.0
 3,000–3,499 grams4.44.33.72.92.42.12.22.1
 3,500–3,999 grams3.23.02.62.01.71.51.51.4
 4,000 grams or more3.33.22.42.01.61.51.61.5
  4,000–4,499 grams2.92.92.21.81.51.41.51.4
  4,500–4,999 grams3.93.82.52.22.11.52.21.9
  5,000 grams or more414.414.79.88.5*6.1*4.9*4.6*5.4
*

Estimates are considered unreliable. Rates preceded by an asterisk are based on fewer than 50 deaths in the numerator.

1

Rates based on unweighted birth cohort data.

2

Rates based on a period file using weighted data; unknown birthweight imputed when period of gestation is known and proportionately distributed when period of gestation is unknown. See Appendix I, National Vital Statistics System (NVSS), Linked Birth/Infant Death Data Set.

3

For calculation of birthweight-specific infant mortality rates, unknown birthweight has been distributed in proportion to known birthweight separately for live births (denominator) and infant deaths (numerator).

4

In 1989, a birthweight-gestational age consistency check instituted for the natality file resulted in a decrease in the number of deaths to infants coded with birthweights of 5,000 grams or more and a discontinuity in the mortality trend for infants weighing 5,000 grams or more at birth. Starting with 1989 data, the rates are believed to be more accurate.

NOTES: National linked files do not exist for 1992–1994. Data for additional years are available. See Appendix III.

SOURCE: CDC/NCHS, National Vital Statistics System, Linked Birth/Infant Death Data Set.

From: Trend Tables

Cover of Health, United States, 2010
Health, United States, 2010: With Special Feature on Death and Dying.
National Center for Health Statistics (US).
Hyattsville (MD): National Center for Health Statistics (US); 2011 Feb.

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