Infant mortality is a measure of how many babies die during the first 12 months after birth. It is usually measured as being a number of deaths for every thousand births. The rate of infant mortality in a given place is the total number of babies dying under one year of age divided by the total number of live births during the year, then all multiplied by 1,000. For example, in 2009 the infant mortality rate in the USA was 6.8. That means for every 1000 births, 6.8 babies will die before the age of one.