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Births and Deaths: Year ended September 2011
Embargoed until 10:45am  –  17 November 2011
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 New Zealand 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. 


Birth and death figures contained in the tables attached to this information release are unrounded. All other figures have been rounded. This may result in a total differing slightly from the sum of its components. Derived figures (eg percentage annual increase) have been calculated using unrounded data.


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

More information

For more technical information, see Information about Births or Information about Deaths.

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. For more information about the history and characteristics of late registrations, see Late birth registrations

Children of this relationship
The birth registration forms ask 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 information 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 7 weeks of the end of the reference period.

Timed statistical releases are delivered using postal and electronic services provided by third parties. Delivery of these releases may be delayed by circumstances outside the control of Statistics NZ. Statistics NZ accepts no responsibility for any such delays.


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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