Washington: Infant mortality Note: An infant is a child under one year of age. The infant mortality rate is calculated by dividing the number of infant deaths by the number of live births. It is presented on a "per 1,000" basis. Source: 1997-2020: Idaho Department of Health and Welfare (http://www.healthandwelfare.idaho.gov/Health/HealthStatistics/tabid/102/Default.aspx); 1997-2020: National Center for Health Statistics, Birth Data (http://www.cdc.gov/nchs/births.htm); and Death Data (http://www.cdc.gov/nchs/deaths.htm); DATE LAST UPDATED: April 12, 2023.