Priority Indicator #15: Infant Mortality Rate

Contents: Background Information | Data Tables | Data Charts | Commentary | Download Data

Background Information

What Does This Indicator Mean?
Infant mortality rate provides a partial measure of the overall health status of a community.  It is often correlated with population health factors such as immunization rates, access to health care and teen pregnancy.

Referring to a specific time period and geographic region, this indicator measures the proportion of infants who die within the first year of life (less than 365 days) divided by the total number of live births in the region, multiplied by 1,000.

Other Risk Factors or Indicators to Consider
While the causes of infant mortality are in many cases are unknown, several indicators are related to infant mortality rate.  Health indicators such as the percentage of the population with adequate access to health care (insurance rate), utilization of prenatal care, teen pregnancy rate and rate of low birth weight babies should all be analyzed in conjunction with this measure.  In addition, socio-economic and demographic factors such as ethnic distribution, poverty rate and child abuse statistics should be consulted.

Limitations of the Data
Infant mortality rates presented here are aggregated for a combined three-year period to ensure confidentiality and statistical validity.  This indicator is not reported at the zip code level because of the low incidence of infant deaths and births in each zip code.

Data Sources

  • Center for Health Statistics, Oregon Health Division, Oregon Department of Human Services

  • Centers for Disease Control WONDER Data System

Presentation and Discussion of the Data

The table below shows infant mortality per 1,000 live births for Oregon as a whole, and the total for Marion and Polk Counties.

Geographic Region

 Infant Deaths/1,000 Live Births (1995-1997)

Infant Deaths/1,000 Live Births (1997-1999)

Infant Deaths/1,000 Live Births (1999-2001)

Oregon 5.9 5.7 5.6

Marion County

7.5

5.9

5.8

Polk County

3.9

3.9

3.7

Source: Oregon Health Division data, compiled by Marion-Polk CHIP. http://www.willamette.edu/publicpolicy/chip 

It is worth noting that the Polk County rate is based on only eight infant deaths in the 1997-99 and 1999-2001 period, while the Marion County rate is based on 80 and 79 infant deaths, respectively.  The state rate is based on 763 infant deaths during 1997-1999 and 761 infant deaths during 1999-2001.

The chart below shows infant mortality rates between 1991 and 2001 in Marion and Polk Counties and statewide.

Commentary

The infant mortality rate statewide declined between 1990 and 1996, from 8.3 deaths per 1,000 in 1990 to 5.6 in 1996.  The rate remained relatively constant between 1996 and 2001, when the rate approximately 5.7 deaths per 1,000 births.

The infant mortality rates in both Marion and Polk Counties have fluctuated considerably.  In Marion County the rate increased from 6.3 in the 1991-93 period to 7.5 for 1995-97, and then declined to 5.8 during the years 1999-2001.  Polk County’s rate has been even more volatile, primarily because of the small number of births and deaths in the county.

In any given year, only a few of the zip codes in Marion and Polk Counties had more than 5 infant deaths.  A low incidence of total births and infant deaths in each county makes it impossible to accurately compare figures at the sub-county level.  FOR THESE REASONS, IT IS RECOMMENDED THAT THIS INDICATOR NOT BE EXAMINED AT THE COMMUNITY/SUB-COUNTY LEVEL IN THE FUTURE OR THAT ANY SUB-COUNTY ANALYSIS BE EITHER AT THE GROUPED ZIP CODE LEVEL (E.G., LEGISLATIVE OR SCHOOL DISTRICTS) OR AS A ROLLING MULTI-YEAR AVERAGE.

It should be noted that the lack of events at the sub-county level may in fact provide important information.  For example, while the majority of zip codes within Marion and Polk Counties had fewer than 5 events per year, the regions that did have reportable rates for multiple years (zip codes 97301, 97303, 97305) are in a contiguous region in North Salem, an area with above average rates of poverty, unemployment, and being uninsured.

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This page last updated 25 April 2003