The growth of natural population in New Zealand has been found to have declined the most in 2013 with a majority of women in the country postponing child rearing.

Data released by Statistics New Zealand on Wednesday showed live births registrations were only 58,717 cases in 2013, down 4 per cent or by 2,461 cases from 2012.

Analysts in Statistics New Zealand said the reason could be due to more women deciding to postpone having kids

In 2013, more women aged 35 to 39 years old gave birth, at 71 babies per 1,000 women, overtaking births by women aged 20 to 24 for the first time, which registered at only 67 babies per 1,000.

Andrea Blackburn, population statistics manager, noted the country's future population size and age will remain influenced by reigning number of births. It was in 1961 when New Zealand had its biggest number of births recorded in any year at 65,390. At that time, New Zealand's population was 2.5 million versus 2013's 4.5 million.

Live birth minus deaths, New Zealand's 2013 natural population increase was only 29,149, the lowest natural increase from 2003's record of 28,124.

The number of deaths meantime in New Zealand dropped 2 per cent in 2013 to 29,568 from 30,099 in 2012. The regions of Auckland and Canterbury yielded the largest number of deaths in 2013 at 7,566 and 4,098, respectively.

In mid February, the New Zealand Institute for Economic Research (NZIER) recommended to the national government to open doors and allow the entry of an extra 40, 000 immigrants per year to help boost the growth of the national economy.