In 2010 the Age-standardized mortality rate was 3.8 deaths per 1000 (down from 4.8 in 2000) and the infant mortality rate for the total population was 5.1 deaths per 1000 live births.

 The life expectancy of a New Zealand child born in 2008 was 82.4 years for females, and 78.4 years for males. Life expectancy at birth is forecast to increase from 80 years to 85 years in 2050 and infant mortality is expected to decline.

 In 2050 the population is forecast to reach 5.3 million, the median age to rise from 36 years to 43 years and the percentage of people 60 years of age and older rising from 18 percent to 29 percent.

During early migration in 1858, New Zealand had 131 males for every 100 females, but following changes in migration patterns and the modern longevity advantage of women, females came to outnumber males in 1971.As of 2012 there are 0.99 males per female, with males dominating under 15 years and females dominating in the 65 years and older range.

English is the predominant language in New Zealand, spoken by 98 percent of the population. New Zealand English is mostly non-rhotic with an exception being the Southern Burr found principally in Southland and parts of Otago.

It is similar to Australian English and many speakers from the Northern Hemisphere are unable to tell the accents apart. In New Zealand English the short i (as in kit) has become centralised, leading to the phrase fish and chips sounding like "fush and chups" to the Australian ear. The words rarely and really, reel and real, doll and dole, pull and pool, witch and which, and full and fill can sometimes be pronounced as homophones.

 Some New Zealanders pronounce the past participles grown, thrown and mown using two syllables, whereas groan, throne and moan are pronounced as one syllable.[65] New Zealanders often reply to a question or emphasise a point by adding a rising intonation at the end of the sentence.

From 1880 Māori MPs in parliament were keen that Māori should be taught in English rather than Māori.

 At that time missionary schools still taught Māori. This trend was further enforced by the Young Maori Party of the early 20th century which consisted of highly qualified Western educated Māori graduates such as Pomare and Ngata who believed that learning English would help Māori integrate into the modern world. After WW2 Māori, who had previously lived mainly in isolated rural areas migrated into urban areas where there were few Māori speakers.

 Māori were discouraged from speaking their own language (te reo Māori) in schools and work places and it existed as a community language only in a few remote areas.It has recently undergone a process of revitalisation, being declared an official language in 1987, and is spoken by 4.1 percent of the population.

There are now Māori language immersion schools and two Māori Television channels, the only nationwide television channels to have the majority of their prime-time content delivered in Māori.

Many places have officially been given dual Māori and English names in recent years. Samoan is the most widely spoken non-official language (2.3 percent), followed by French, Hindi, Yue and Northern Chinese.New Zealand Sign Language is used by approximately 28,000 people and was made New Zealand's third official language in 2006.