Study charts NZ's dramatic rise in lifespan

New Zealanders born today can expect to live more than 25 years longer than those born in the late 1870s, when almost a quarter of people did not even see their 15th birthdays.

The dramatic difference is detailed in a pioneering study of mortality, A History of Survival in New Zealand, which has followed the lives of all New Zealanders born from the 1870s.

The study by Statistics New Zealand reveals that of those born in the late 1870s, 23 per cent never reached their 15th birthdays. This death rate drops to 15 per cent for those born in the 1900s, and to just 1 per cent for those born around 1990.

As a consequence, the average lifespan for a male New Zealander born in the late 1870s was just 51, and for a female, 55.

The study also reveals that 10 per cent of New Zealand males born in the mid-1890s died as a result of war.

"Without the direct impact of deaths in World Wars I and II, life expectancy at birth would have been five years higher for males born in the mid-1890s, and three years higher for males born in the late 1910s," the study says.

The most recent lifespan expectations, for those born from 2003 to 2005, are that men can now expect to live to about 77 and women to about 81.

Statistics NZ demographer Kim Dunstan said the study provided the most complete picture of how long New Zealanders lived and showed for the first time the impact of war deaths on the population.

"Death comes to us all and it does affect us at a lot of levels. A lot of people have had family members who died in the war and can relate to their own experiences," Mr Dunstan said.

The study was unique in following a population from life to death.

It was possible because New Zealand was one of the few countries with relatively complete and detailed birth, death and migration information dating back to the late 1800s.

Mr Dunstan said the dramatic lifespan changes were attributed to many factors, including improved hygiene, sanitation, medicines and infectious disease control. Changes in lifestyle had also made an important difference.

The study's findings were important in determining New Zealand's future needs in the likes of healthcare and superannuation.

"We see the study very much as the basis for further work ... across other organisations in New Zealand and, indeed, internationally.

"It's only natural that those interested in these sorts of patterns will be re-assessing their own on the basis of these studies."