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Births and Deaths: Year ended December 2014
Embargoed until 10:45am  –  18 February 2015
Data quality

This section contains information about data that does not change between releases.

Data source

Under the provisions of the Births, Deaths, Marriages, and Relationships Registration Act 1995, every birth and death occurring in New Zealand must be registered with Births, Deaths and Marriages (a division of the Department of Internal Affairs).

Statistics NZ receives a monthly electronic file of registered births and deaths from Births, Deaths and Marriages. Statistics NZ is responsible for processing and publishing statistics derived from the birth and death registrations. 

Accuracy of the data

Births data from 1991 are based on births registered in New Zealand to mothers resident in New Zealand by date of registration. Before 1991, births data are based on births registered in New Zealand to mothers resident in New Zealand and mothers visiting from overseas by date of registration. Births data exclude late registrations under section 16 of the Births, Deaths, Marriages, and Relationships Registration Act 1995. Section 16 births are those that were not registered in the ordinary way at the time the birth occurred. Annual registrations for births may differ from the actual number of events in a given year due to the lag between the date of birth and the date of registration and a small number of events that may never be registered.

Late birth registrations has more information about the history and characteristics of late registrations. 

Neonatal infant deaths
Annual registrations for neonatal (infants under four weeks of age) deaths may differ from the actual number of events in a given year due to the lag between the date of death and the date of registration, and also under-registration. Neonatal and infant mortality rates may underestimate the actual rate in some years especially for Māori and Pacific children and annual fluctuations should be interpreted with caution.

Neonatal deaths include very low birth weight extremely preterm live births. A baby is born alive if the baby breathes or shows any other evidence of life, such as beating of the heart, pulsation of the umbilical cord or definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the placenta is attached. All liveborn infants should be registered and counted as such, irrespective of length of gestation or whether alive or dead at the time of registration. If they die at any time following birth, they should also be registered and counted as deaths.

The World Health Organization defines low birth weight as less than 2.5 kilograms and extremely preterm as a birth before 28 completed weeks of gestation.

Children of this relationship
The birth registration form asks whether there are any other children of this relationship. However, it is possible that children from previous relationships are included. This question does not produce an accurate measure of all live births to a woman (which is needed for accurate measures of birth parity). For privacy reasons, it is deemed unacceptable to ask women about children outside their current relationship.

Deaths data from 1991 onwards are based on deaths registered in New Zealand of New Zealand residents by date of registration. Before 1991, deaths data are based on deaths registered in New Zealand of New Zealand residents and people visiting from overseas by date of registration.

Demographic rates
Demographic rates from 1991 onwards are calculated using the mean estimated resident population. Rates before 1991 are calculated using the mean estimated de facto population.

Demographic rates based on the mean estimated resident population are provisional for the reference period of this information release because the population estimates used to calculate the rates are provisional. Publication of final rates in Infoshare will coincide with the publication of the next quarterly data release. The difference between provisional and final rates is generally small (less than plus or minus 1 per 100,000).

Age-specific fertility rates, median age of mother, and total fertility rates before 1981 are based on December years.

Replacement level fertility
Replacement level fertility is the average number of children a woman needs to have to produce one daughter who survives to childbearing age. Replacement level fertility is also described as the total fertility rate required for the population to replace itself in the long term, without migration.

The internationally accepted replacement level is 2.1 births per woman. Replacement level fertility allows for child mortality (children who die before reaching reproductive age) and the birth of more boys than girls. On average, throughout the world, 105 boys are born for every 100 girls. The actual replacement level will vary slightly from country to country, depending on child mortality rates. In countries with high child mortality, the total fertility rate will need to be higher than 2.1 births per woman to achieve replacement level. 

Timing of published data

Statistics NZ aims to publish Births and Deaths within seven weeks of the end of the reference period.

Our information releases are delivered electronically by third parties. Delivery may be delayed by circumstances outside our control. Statistics NZ accepts no responsibility for any such delays.


In order to comply with Statistics NZ's confidentiality protocols, some categories are collapsed or aggregated in tables and datasets.

More information

See Information about Births or Information about Deaths for more technical information.

Statistics in this release have been produced in accordance with the Official Statistics System principles and protocols for producers of Tier 1 statistics for quality. They conform to the Statistics NZ Methodological Standard for Reporting of Data Quality.


While care has been used in processing, analysing, and extracting information, Statistics NZ gives no warranty that the information supplied is free from error. Statistics NZ shall not be liable for any loss suffered through the use, directly or indirectly, of any information, product, or service.

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