How To... - Interpret Data - Case Studies - Low Birthweight
When: Is low birthweight increasing or decreasing over time?

	More info on Low Birthweight Case Study: Is low birthweight a health problem? Is it changing over time? Where is the problem? Who is affected? Is it changing among specific groups over time?

The PNSS Table 19C, Summary of Trends in Infant Health Indicators, provides trends of low birthweight and high birthweight for all years that the contributor has participated in PNSS. This table can be used to look at recent changes in the prevalence of low birthweight by comparing the prevalence in 2002 with the previous year and it can be used to look at changes that have occurred over longer periods.

Sample: PNSS Table 19C, Summary of Trends in Infant Health Indicators

	The prevalence of low birthweight remained the same at 7.7% from 2001 to 2002.
	The first year of data available was 1993.
	The prevalence of low birthweight infants decreased slightly from 9.1% in 1993 to 7.7% in 2002. The percentage decrease or relative decrease during this time period is 18% ((9.1 minus 7.7)/7.7 = 0.18 x 100 = 18 %).

This line chart, derived from Table 19C, shows a slight decrease in the prevalence of infants who were low birthweight between 1993 and 2002.

When? Is low birthweight increasing or decreasing over time?

The prevalence of low birthweight has decreased slightly from 1993 and 2002. The relative decrease during this time period was 18%.

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This page last updated April 11, 2005

United States Department of Health and Human Services
Centers for Disease Control and Prevention
National Center for Chronic Disease Prevention and Health Promotion
Division of Nutrition and Physical Activity