A country records declining infant mortality, declining maternal mortality, rising life expectancy, and improving healthcare facilities over three decades. Which change in age structure is most consistent with these trends?

A smaller proportion of the population in younger age groups and a larger proportion in older age groups.

The correct answer is Option 3: A smaller proportion of the population in younger age groups and a larger proportion in older age groups.

Option 1: A larger proportion of the population in younger age groups because more children survive infancy. Incorrect. It is true that declining infant mortality allows more children to survive. However, the question asks about the overall long-term change in age structure. Improvements in healthcare and life expectancy increase survival across all age groups, especially into older ages. Therefore, the dominant trend is population ageing rather than a growing share of younger people.

Option 2: A smaller proportion of the population in older age groups because declining mortality reduces the need for larger families. Incorrect. This option mixes two different demographic concepts. Declining mortality and rising life expectancy generally increase the proportion of older people because more individuals survive to advanced ages. Changes in family size preferences do not negate this effect.

Option 3: A smaller proportion of the population in younger age groups and a larger proportion in older age groups. Correct. As mortality falls and life expectancy rises, more people survive into old age. Over time, this increases the proportion of older persons in the population and reduces the relative share of younger age groups.

Option 4: A larger proportion of the population in both younger and older age groups with no change in the middle-age population. Incorrect. Age structure is interconnected. When the proportion of older age groups rises, there is usually a corresponding change in the proportions of younger and working-age groups. There is no reason to assume that the middle-age population would remain unaffected while both ends of the age structure expand simultaneously.