Age-specific mortality rate
An age-specific mortality rate is a mortality rate limited to a particular age group. It is used to compare the mortality rates without being affected by the difference in age distributions.
The numerator is the number of deaths in that age group.
The denominator is the number of persons in that age group in the population.
Infant mortality rate
Infant mortality rate is the probability of a child born in a specific year or period dying before reaching the age of one. It reflects the health of the mother and infant during pregnancy and the year after that.
The numerator is the number of deaths among children < 1 year of age during a given time interval.
The denominator is the number of live births during the same time interval.