Pākehā age structures have changed over time and are influenced by fertility, mortality and migration patterns. When fertility is high and mortality declines (creating the beginning of a demographic transition), the proportion of children in the population is high. This occurred in the 19th century, though it was diluted by the immigration of working-age people (aged 15–64). The child population rose throughout the 19th century but went down during the 1930s economic depression because women were marrying later and having far fewer children, or not marrying at all.
Declining fertility rates led to concerns that there would be few children in New Zealand in the early 20th century. In St Patrick’s Cathedral in Auckland in 1912, a clergyman described childless women as ‘many whitened sepulchres parading the streets, adorning their bodies with all that money can buy, despising the authority of God and refusing to do what God has decreed.’ He said their childlessness led to ‘empty cradles [and] an absence of little ones from the schools built at great cost to the country.’ 1
When fertility starts to decline but there are still low numbers of older people, the proportion of working-age people increases. This pattern occurred in the Pākehā population in the first third of the 20th century. In contrast to the child population, which dropped as a proportion, the working-age adult population grew during the depression, though more slowly than previously.
The child population grew and peaked during the post-Second World War baby boom, when past patterns of early marriage and high fertility recurred. As a result, the working-age group as a proportion of the total population dropped. This trend was reversed in the 1970s. Fertility rates dropped significantly and the large group of baby boomers grew into adulthood (and had fewer children). In 2013 New Zealand’s total population was almost double what it had been in 1956, but the number of children was almost the same.
The most significant age structure trend to emerge from the late 20th century was the increasing proportion of the population aged 65 and above. In 2017 the older population accounted for just over 15% of the total population. It is projected to increase to 20% in 2031. By the 2020s there will be more people over 65 than under 15. This change is called structural ageing.
Pākehā dependency ratios (the notional support burden placed on the working-age population by younger and older people) were high in the 19th century despite large working-age immigrant populations, because fertility was high – there were a lot of children to care for. This changed later in the century as those children became adults and fertility rates declined, although children aged 0–14 years still accounted for one-third of the population at the beginning of the 20th century. Total dependency ratios were low from the late 19th century until the Second World War. During the baby boom the economy struggled to meet the demands of the large number of children (such as schools and paediatric care). Children aged 0–14 years continued to account for between one-third and one-quarter of the population until the 1980s.
Dependency ratios dropped after this and remain relatively low in the early 21st century. This will change as the population ages, though total dependency ratios will still be lower in the 2050s than they were during the baby boom. From the 2020s older people will influence dependency ratios more than children.
Changes in the population age structure and dependency have significant implications for the entire economy and society. This is because they affect the size of the labour force and amount of ‘human capital’, which in turn affects taxation income and household income and savings. During periods when New Zealand’s working-age population was high, and child and older populations relatively low, there have been windows of opportunity to make major investments in infrastructure and productive industries.
These potential gains have been termed 'demographic dividends'. They can occur as societies transition from youthful, fast-growing structures to older, slower growing structures. One such dividend has the potential to arise when the proportion of the population at the main working ages reaches its maximum, and the proportion at older and younger is at its minimum. While the total New Zealand population passed through this historical moment around 2011, Māori will have this potential for several more decades due to the youthful age structure of its population. There is even potential for a 'collateral' dividend as the proportion of younger Māori labour market entrants increases compared to that of the structurally older European population, which has greater proportions approaching retirement.
An ageing population potentially means there will be fewer people of working age paying income tax, more people accessing government-funded superannuation, and greater demand on health and social services. However, it is likely that older people will continue in paid employment for longer, which will offset these costs to some extent.