The death rate during the first year of life(noun)
WordNet. Princeton University. 2010.
Use "infant mortality rate" in a sentence
"Sometimes the conversation will center on statistics-the infant mortality rate (on par with Malaysia among poor black Americans), or black male unemployment (estimated at more than a third in some Chicago neighborhoods), or the number of black men who can expect to go through the criminal justice system at some point in their lives (one in three nationally)."