Key concept: computing the infant mortality rate
The infant mortality rate (IMR) is a classic vital statistic used to describe the health of a community. It is calculated as the number of deaths of infants under
1 year of age in a given year, divided by the number of live births in that same year, then multiplied by
1,000. The formula is:
IMR = (deaths under 1 year ÷ live births) × 1,000
In this municipality, the numerator is
31 infant deaths, and the denominator is
1,240 live births. The midyear population of
62,000 is not used in this calculation because the IMR is a ratio of infant deaths to live births, not a rate per total population. The computation is:
31 ÷ 1,240 × 1,000 = 25.0 per 1,000 live births
The numerator includes all infant deaths, meaning both neonatal deaths (within the first
28 days of life) and post-neonatal deaths (from
28 days up to
1 year). In this case,
18 deaths were neonatal, and the remaining
13 were post-neonatal. Both are counted in the IMR.
Watch out! The denominator is live births, not the midyear population. Using
62,000 would produce a completely different and incorrect value.
Key point! The IMR is a sensitive indicator of maternal and child health, access to prenatal care, nutrition, sanitation, and the overall effectiveness of the health system. Because it reflects conditions affecting the most vulnerable age group, it is often used to compare health status across communities or over time.
The abstract by Reidpath and Allotey notes that the IMR has been criticized for being narrowly focused on a small segment of the population
[1]. However, it remains widely used, especially in resource-limited settings, because it is relatively simple to calculate and interpret compared with more comprehensive measures such as disability-adjusted life expectancy. For a rural health unit preparing an annual report, the IMR provides a practical and actionable summary of infant survival in the municipality.
| Component | Value in this problem | Role in IMR |
|---|
| Deaths under 1 year | 31 | Numerator |
| Live births | 1,240 | Denominator |
| Midyear population | 62,000 | Not used |
| Neonatal deaths (first 28 days) | 18 | Included in numerator |
| Post-neonatal deaths (28 days to 1 year) | 13 | Included in numerator |
The correct answer is therefore
25.0 per
1,000 live births.
References (research sources)