EXPLANATORY NOTES


INTRODUCTION

1 This release contains statistics for births and fertility in Australia. Detailed information can be obtained from data cubes (in Microsoft Excel format) available electronically from the Downloads tab of this release on the ABS website.

2 A glossary is provided detailing definitions of terminology used. A list of abbreviations is also available.


SCOPE AND COVERAGE

3 Statistics in this release relate to the number of births registered during the calendar year shown, unless otherwise stated. Statistics relating to births by year of occurrence can be obtained from data cubes available electronically from the Downloads tab of this release on the ABS website.


Scope of birth statistics

4 The ABS Birth Registrations collection includes all births that occurred and were registered in Australia, including births to mothers whose place of usual residence was overseas.

5 The scope of the statistics includes:

• all births that were live born and were not previously registered;
• births to temporary visitors to Australia (including visitors from Norfolk Island);
• births that occurred within Australian Territorial waters;
• births that occurred in Australian Antarctic Territories and other external territories (excluding Norfolk Island);
• births that occurred in transit (i.e. on ships or planes) if registered in the Australian state or territory of 'next port of call';
• births to Australian nationals employed overseas at Australian legations and consular offices (i.e. children born overseas to Australian diplomats or their families); and
• births that occurred in earlier years that have not been previously registered (late registrations).

6 The scope of the statistics excludes:

• still births/fetal deaths (these are accounted for in perinatal death statistics published in Perinatal Deaths, Australia (cat. no. 3304.0), and previously, Causes of Death, Australia (cat. no. 3303.0));
• adoptions, sex changes, legitimations and corrections;
• births to foreign diplomatic staff; and
• births occurring on Norfolk Island.

7 The scope for each reference year of the Birth Registrations collection includes:

• births registered in the reference year and received by the ABS in the reference year;
• births registered in the reference year and received by the ABS in the first quarter of the subsequent year; and
• births registered in the years prior to the reference year but not received by the ABS until the reference year or the first quarter of the subsequent year, provided that these records have not been included in any statistics from earlier periods.

8 Birth records received by the ABS during the March quarter of 2014, which were registered in 2013, were assigned to the 2013 reference year. Any registrations relating to 2013 which were received by the ABS from April 2014 were assigned to the 2014 reference year.

9 Prior to 2007, the scope for the reference year of the Birth Registrations collection included:

• births registered in the reference year and received by the ABS in the reference year;
• births registered in the reference year and received by the ABS in the first quarter of the subsequent year; and
• births registered during the two years prior to the reference year but not received by the ABS until the reference year.

Coverage of birth statistics

10 Ideally, for compiling annual time series, the number of births should be recorded as all those occurring within a given reference period such as a calendar year. Due to lags in registration of births and the provision of that information to the ABS from state and territory Registrars of Births, Deaths and Marriages, data in this release are presented on a year of registration basis.

11 In effect there are three dates attributable to each birth registration:

• the date of occurrence (of the birth);
• the date of registration or inclusion on the state/territory register; and
• the month and year in which the registered birth is provided to the ABS.

12 Data in this release are presented according to date of registration, unless otherwise stated. The registration date differs between states and territories, and should be taken into account when analysing birth statistics:

• For births registered in New South Wales, Victoria, Western Australia and the Australian Capital Territory, the birth registration date is the date at which the record is entered into the registration processing system.
• For births registered in Queensland, the registration date is the date at which all data on the birth record are finalised. This may be before the birth is entered into the registration system.
• For births registered in South Australia, preliminary and final registration dates are allocated. Where a record requires further information a preliminary date is assigned. Once all data are finalised, a final registration date is assigned to the birth record which is provided to the ABS as the registration date.
• For births registered in Tasmania, a date is allocated when the birth record is entered into the registration system. The ABS receives an 'insertion' date which is the date when any information relating to the birth is entered into the registration system and this is the registration date.
• For births registered in the Northern Territory, the registration date is the date at which the record is entered into the registration system. For birth records not received by the Registrar within 60 days of the birth, the Registrar will register the child as 'unnamed' and not finalised.

CLASSIFICATIONS

Marital status

13 Marital status relates to the registered marital status of the parents at the time of birth and refers to formally registered marriages or divorces for which a certificate is held.


Nuptiality

14 Nuptiality relates to the registered marital status of the parent(s) of the child at the time of birth. Confinements and births are classified as:

• nuptial where the father registered was married to the mother at the time of the child's birth, or where the husband died during the mother's pregnancy (confinements and births to Aboriginal and Torres Strait Islander mothers considered to be tribally married to the father of the child are classified as nuptial); and
• ex-nuptial where the parents were not in a registered marriage at the time of the child's birth, irrespective of whether the parents were living together at the time of the birth.

15 Ex-nuptial births and confinements are further classified as paternity acknowledged (where the father signed the birth registration form) or paternity not acknowledged (where the father did not sign the birth registration form).


Geography

16 This issue of Births, Australia includes data cubes containing birth and fertility statistics on the Australian Statistical Geography Standard (ASGS) and the Standard Australian Classification of Countries (SACC), Second Edition.

17 For further information, refer to Australian Statistical Geography Standard (ASGS): Volume 1 - Main Structure and Greater Capital City Statistical Areas, July 2011 (cat. no. 1270.0.55.001) and Standard Australian Classification of Countries (SACC) (cat. no. 1269.0).


DATA SOURCES

18 Registration of births is the responsibility of state and territory Registrars of Births, Deaths and Marriages and is based on data provided on an information form completed by the parent(s) of the child. This form is the basis of data provided to the ABS by the Registrars for compilation into aggregate statistics in this release. Core data items are collected in all states and territories and therefore statistics at the national level are available for key characteristics. Some states collect additional information.

19 Hospitals and birth clinics notify state and territory registries of recent births on a regular basis. For births where a notification has been received by a registry, but has not been registered within the prescribed time period, a reminder letter is sent to the parent(s) of the child.


State and territory data

20 As a result of an amendment made in 1992 to section 17(a) of the Acts Interpretation Act 1901-1973 (Cwlth), the Indian Ocean territories of Christmas Island and Cocos (Keeling) Islands have been included as part of geographic Australia since 1993, hence another category of the state and territory classification has been created. This category is known as 'Other Territories' and includes Christmas Island, the Cocos (Keeling) Islands and Jervis Bay Territory.

21 Prior to 1993, births to mothers usually resident in Christmas Island or Cocos (Keeling) Islands were included with Offshore areas and Migratory in Western Australia, while births to mothers usually resident in Jervis Bay Territory were included with the Australian Capital Territory. In 2013, there were 27 births to mothers usually resident in Christmas Island, the Cocos (Keeling) Islands, or Jervis Bay Territory.

22 Birth statistics for states and territories have been compiled and presented according to the state or territory of usual residence of the mother regardless of where in Australia the birth occurred and was registered, except where otherwise stated. In the following table, data are presented on both a state or territory of registration basis and usual residence basis. Births which took place outside Australia are excluded from the statistics. Births to mothers who were usual residents of Australia's Other Territories (Christmas Island, Cocos (Keeling) Islands and Jervis Bay Territory) cannot be registered in Other Territories but are registered in other Australian states and territories.

Births, State or territory of usual residence of mother and state or territory of registration - 2013
	State of territory of registration
State or territory of usual residence	NSW	Vic.	Qld	SA	WA	Tas.	NT	ACT	Aust.
New South Wales	97 638	1 182	634	56	43	4	6	899	100 462
Victoria	101	73 742	35	55	20	9	3	4	73 969
Queensland	1 044	65	62 201	5	29	4	np	np	63 354
South Australia	29	38	np	19 955	20	np	34	-	20 090
Western Australia	56	34	28	16	34 349	4	29	-	34 516
Tasmania	10	17	np	-	np	6 014	-	-	6 049
Northern Territory	32	np	39	31	29	np	3 905	np	4 053
Australian Capital Territory	147	9	9	-	np	-	np	5 373	5 545
Other Territories	np	np	-	-	19	-	-	-	27
Australia	99 064	75 103	62 964	20 118	34 516	6 038	3 981	6 281	308 065
- nil or rounded to zero (including null cells)
np not available for publication but included in totals where applicable, unless otherwise indicated

23 In 2013, there were 320 births registered in Australia to women who usually lived overseas. These have been included in this release with state or territory of usual residence classified according to the state or territory in which the birth was registered.

Births, Mother usually resident overseas - 2006 to 2013
State or territory of registration	2006	2007	2008	2009	2010	2011	2012	2013
New South Wales	310	327	346	253	311	267	292	272
Victoria	21	17	20	23	13	9	np	8
Queensland	41	86	42	27	21	20	31	26
South Australia	np	3	3	np	-	np	-	-
Western Australia	13	21	18	13	np	8	10	11
Tasmania	-	-	-	-	-	-	-	np
Northern Territory	4	np	np	np	np	np	np	np
Australian Capital Territory	np	np	np	-	np	np	-	-
Australia	393	459	434	324	356	308	339	320
- nil or rounded to zero (including null cells) np not available for publication but included in totals where applicable, unless otherwise indicated

Sub-state/territory fertility rates

24 Age-specific and total fertility rates for sub-state/territory regions (for example, Statistical Areas Level 2) presented in data cubes released with this release are average rates for three years ending in the reference year. Rates for Australia and the states and territories in all other tables are based on single years of birth registration data.


DATA QUALITY

25 In compiling birth statistics, the ABS employs a variety of measures to improve the quality of the birth registrations collection. While every opportunity is taken to ensure that the highest quality of statistics are provided, the following are known issues associated with the statistics included in this release.


Interval between occurrence and registration of births

26 For the most part, statistics in this release refer to births registered during the calendar year shown. There is usually an interval between the occurrence and registration of a birth (referred to as a registration 'lag') and as a result, some births occurring in one year are not registered until the following year or later. This can be caused by either a delay by the parent(s) in submitting a completed form to the registry, or a delay by the registry in processing the birth. Births which occur in November and December are also likely to be registered in the following year.

Births registered in 2013, Year of occurrence
	2006 and earlier	2007	2008	2009	2010	2011	2012	2013
State or territory of registration	%	%	%	%	%	%	%	%
New South Wales	1.5	0.2	0.3	0.3	0.3	0.5	11.6	85.3
Victoria	0.6	0.1	0.2	0.2	0.4	0.6	11.7	86.2
Queensland	1.6	0.3	0.4	0.4	0.3	0.5	9.7	86.7
South Australia	1.2	0.1	0.1	0.1	0.1	0.2	8.1	90.1
Western Australia	1.8	0.2	0.2	0.2	0.2	0.4	7.7	89.4
Tasmania	2.8	-	-	-	-	-	2.7	94.5
Northern Territory	0.3	-	-	-	-	-	6.3	93.3
Australian Capital Territory	0.2	-	0.1	0.1	0.1	0.2	9.5	89.7
Australia	1.3	0.2	0.2	0.2	0.3	0.5	10.3	87.0
- nil or rounded to zero (including null cells)

27 Of the 308,065 births registered in Australia in 2013, 87.0% occurred in 2013, 10.3% occurred in 2012 and the remainder (2.7%) occurred in 2011 or earlier years.


Effects of registration lags on multiple birth statistics

28 It has been observed in recent years that there are a small number of twin and higher order births from the same confinement that are registered in different reference years. Due to this reason, the number of twin and higher order births registered in a reference year may not exactly match the number of such confinements registered in that year. For more information on the coverage of a reference year, see paragraph 8.


Recent registration lags in Queensland

29 As a result of changes in the timeliness of registration of births in Queensland, care should be taken when interpreting changes in Queensland births between 2005 and 2010. This lag has reduced in recent years, indicating improvements in the timeliness of registration of births in Queensland.

30 The December quarter of 2009 also saw the Queensland Registry of Births, Deaths and Marriages devoting significant time and resources to follow-up and finalise birth registrations where there was previously incomplete information. As part of the 'Retrospective Births Project', 1,780 births were registered, with approximately 40% registered as Aboriginal and Torres Strait Islander births (see paragraph 39 for more information). This project is now complete.

Births registered in Queensland, Year of registration by year of occurrence
	Year of registration
	2006	2007	2008	2009	2010	2011	2012	2013
Year of occurrence	%	%	%	%	%	%	%	%
2003 and earlier	3.1	2.5	2.8	2.4	1.9	1.5	1.3	1.1
2004	0.8	0.5	0.9	0.6	0.3	0.2	0.1	0.2
2005	14.8	1.1	0.6	1.1	0.7	0.4	0.2	0.1
2006	81.3	16.2	1.1	1.3	0.7	0.8	0.5	0.2
2007	-	79.7	13.2	1.3	0.5	0.7	0.6	0.3
2008	-	-	81.3	12.8	0.5	0.2	0.4	0.4
2009	-	-	-	80.5	11.0	0.4	0.3	0.4
2010	-	-	-	-	84.4	9.2	0.5	0.3
2011	-	-	-	-	-	86.5	8.9	0.5
2012	-	-	-	-	-	-	87.2	9.7
2013	-	-	-	-	-	-	-	86.7
- nil or rounded to zero (including null cells)

Previously unprocessed New South Wales births

31 Questions have been raised over the completeness of the New South Wales (NSW) birth counts in recent years. In response to these concerns the ABS, in conjunction with the NSW Registry of Births, Deaths and Marriages, has undertaken an investigation which has led to the identification of an ABS systems processing error. The ABS acknowledges that this has resulted in previous under-coverage of births in NSW. Data for 2011 was corrected in Births, Australia, 2011 (cat. no 3301.0) and data for 2005-2010 has been corrected in Births, Australia, 2012 (cat. no 3301.0), to ensure that NSW birth and fertility statistics released are correct. For further information see Explanatory Note 12 in Australian Demographic Statistics, Dec 2012 (cat. no. 3101.0) and the Technical Note: Effect of previously unprocessed New South Wales births from Births, Australia, 2011 (cat. no 3301.0).


Tasmanian birth registrations

32 The Tasmanian Births, Deaths and Marriages Registration Act 1999 requires hospitals, doctors, midwives or other responsible persons to provide the Tasmanian Registrar with a list of babies born containing basic information such as date of birth and sex of the baby. In the case of a live birth, the birth notification must be provided within 21 days of the birth. These notifications have been provided to the ABS since 2002 and are also used in producing quarterly population estimates.

33 Under the Act, the birth of a child must also be registered by lodging a birth registration statement with the Registrar within 60 days after the date of birth of the child. Once the parent(s) submits the birth registration statement, the record is updated and the Registrar provides the ABS with a complete registration record. Where a match between a birth notification and birth registration statement is identified, the record is quality assured to ensure completeness of the record.

34 Prior to 2007, records for which a birth registration form was not received were coded as 'ex-nuptial, paternity not acknowledged'. As a result, the number of ex-nuptial births in Tasmania may be overstated for 2002 to 2006. From 2007, these records have been excluded from all nuptiality statistics. These records also affect the completeness of parity statistics, see Explanatory Note 49. From 2013, the ABS no longer received birth notifications, and therefore there are no unmatched birth registration forms in this data.


Aboriginal and Torres Strait Islander births and fertility rates

35 The ABS Birth Registrations collection records a birth as being an Aboriginal and Torres Strait Islander birth where at least one parent reported themselves as being an Aboriginal person, Torres Strait Islander, or both on the birth registration form. Therefore, Aboriginal and Torres Strait Islander births may be attributed to either:

• Aboriginal and/or Torres Strait Islander mothers, including births where both the mother and father are Aboriginal and/or Torres Strait Islander Australians; or
• Aboriginal and/or Torres Strait Islander fathers and non-Indigenous mothers.

36 There are several data collection forms on which people are asked to state whether they are an Aboriginal and/or Torres Strait Islander Australian. Due to a number of factors, the results are not always consistent. The likelihood that a person will report, or be recorded, as an Aboriginal and/or Torres Strait Islander Australian on a specific form is known as their propensity to identify.

37 Propensity to identify and be recorded as an Aboriginal and/or Torres Strait Islander Australian is determined by a range of factors, including:

• how the information is collected (e.g. Census, survey, or administrative data);
• who completes the form;
• the perception of why the information is required, and how it will be used;
• education programs about reporting as an Aboriginal and/or Torres Strait Islander Australian; and
• cultural aspects and feelings associated with reporting as an Aboriginal and Torres Strait Islander Australian.

38 Data presented in this release may therefore underestimate the level of Aboriginal and Torres Strait Islander births and the reliability of Aboriginal and Torres Strait Islander fertility in Australia. Lags in registrations may also affect reliability of measures of Aboriginal and Torres Strait Islander fertility. Caution should be exercised when interpreting Aboriginal and Torres Strait Islander data presented in this release, especially with regard to year-to-year changes.

Aboriginal and Torres Strait Islander births registered in 2013, Year of occurrence - Selected years
	2006 and earlier	2007	2008	2009	2010	2011	2012	2013
State or territory of registration	%	%	%	%	%	%	%	%
New South Wales	7.8	1.2	1.3	1.4	1.3	2.0	13.0	72.1
Victoria	6.1	1.3	1.5	1.7	2.1	4.3	14.5	68.4
Queensland	8.5	1.6	2.0	1.4	1.4	2.1	12.2	71.0
South Australia	10.0	0.4	0.3	0.6	0.9	0.4	12.1	75.2
Western Australia	16.5	1.3	1.2	1.5	1.1	2.9	11.9	63.6
Tasmania	4.0	-	0.2	-	-	-	2.9	93.0
Northern Territory	0.8	-	0.1	-	0.1	0.1	8.0	90.9
Australia(a)	8.5	1.2	1.3	1.2	1.2	2.0	11.9	72.6
(a) Includes the Australian Capital Territory. - nil or rounded to zero (including null cells)

Recent registration lags in Queensland

39 As described in paragraph 29, the Queensland Registry of Births, Deaths and Marriages undertook a 'Retrospective Births Project' during 2009, resulting in the registration of births where there was previously incomplete information. A significant proportion of these births were registered as Aboriginal and Torres Strait Islander births, which has affected fertility data in Queensland for 2009 (see Chapter 4: Effect of delayed birth registrations in Australia in the 2009 issue of Births, Australia (cat. no. 3301.0) for more information). Caution should be exercised when interpreting year-to-year changes for Queensland data.

Aboriginal and Torres Strait Islander births registered in Queensland, Year of registration by year of occurrence
	Year of registration
	2006	2007	2008	2009	2010	2011	2012	2013
Year of occurrence	%	%	%	%	%	%	%	%
2003 and earlier	11.6	10.0	12.9	9.6	9.9	8.1	6.7	5.9
2004	3.1	1.6	4.0	2.3	1.3	1.0	0.8	1.0
2005	19.7	3.5	2.0	4.5	2.4	1.7	1.2	0.7
2006	65.7	18.0	3.4	5.9	2.3	2.6	2.0	0.8
2007	-	66.9	14.4	5.6	1.7	2.1	2.3	1.6
2008	-	-	63.3	16.0	1.7	1.0	1.3	2.0
2009	-	-	-	56.0	13.2	1.4	1.3	1.4
2010	-	-	-	-	67.5	10.8	1.9	1.4
2011	-	-	-	-	-	71.3	10.9	2.1
2012	-	-	-	-	-	-	71.5	12.2
2013	-	-	-	-	-	-	-	71.0
- nil or rounded to zero (including null cells)

Registration of Aboriginal and Torres Strait Islander births in New South Wales

40 Since 2006, the Indigenous status of the mother and father for births registered in New South Wales has not been consistent with other jurisdictions. Specifically, where one parent is an Aboriginal and/or Torres Strait Islander Australian, the other parent will be processed as either 'Aboriginal and Torres Strait Islander' or 'Not stated'. Furthermore, where one parent is 'Non-Indigenous', the other parent will also be processed as 'Non-Indigenous' or 'Not stated'. The Indigenous status of the child, where the birth is registered in New South Wales, is derived from the Indigenous status of either of the parents. The Indigenous status of births registered in New South Wales should therefore be interpreted with caution. The ABS has been advised by the registrar that this matter is being investigated as part of other processing system developments underway.

Aboriginal and Torres Strait Islander births, Indigenous status of parents - 2013
	Indigenous status of father
Indigenous status of mother	Aboriginal and/or Torres Strait Islander	Non-Indigenous	Not stated
Registered in New South Wales
Aboriginal and/or Torres Strait Islander mother	1 241	-	2 551
Non-Indigenous mother	-	-	-
Not stated	2 005	-	-
Registered in the Rest of Australia
Aboriginal and/or Torres Strait Islander mother	4 173	3 274	1 930
Non-Indigenous mother	3 137	-	-
Not stated	53	-	-
- nil or rounded to zero (including null cells)

41 The ABS have investigated recent year-to-year variability in the number of births of Aboriginal and Torres Strait Islander peoples. In 2013, 95 births were to mothers who reported themselves as being an Aboriginal and/or Torres Strait Islander Australian (0.7% of children to Aboriginal and/or Torres Strait Islander mothers), and who were born overseas. Since 2007, these instances have accounted for between less than 1% and 3% of births to Aboriginal and/or Torres Strait Islander mothers. Of these births in 2013, 59% were to mothers born in neighbouring countries in the Pacific, such as New Zealand, Samoa and Papua New Guinea, and of these the majority (35 births) were to mothers who reported themselves as being Torres Strait Islander, or both Aboriginal and Torres Strait Islander on the birth registration form. This may indicate that these mothers are seeking to report their Pacific Islander ancestry (for which provision is not made in the Birth Registration Statement forms in Australia) rather than reporting to be Torres Strait Islanders. However, the 5 births to mothers born in Papua New Guinea in 2013 who reported being Torres Strait Islanders may be correctly recorded. The ABS continues to monitor this and work with Registries to improve quality assurance around these data. However, caution should be exercised when interpreting Aboriginal and Torres Strait Islander data presented in this release.

42 This release reports on the number and characteristics of Aboriginal and Torres Strait Islander births and fertility rates in each state and territory, excluding the Australian Capital Territory and Other Territories. Aboriginal and Torres Strait Islander data for the Australian Capital Territory and Other Territories are not analysed separately due to small numbers, but are included in totals for Australia.

43 The populations used to calculate Aboriginal and Torres Strait Islander fertility rates in this release are estimates and projections of the Aboriginal and Torres Strait Islander female population aged 15-49 years, based on results of the 2011 Census of Population and Housing. For more information, see Estimates and Projections, Aboriginal and Torres Strait Islander Australians, 2001 to 2026 (cat. no. 3238.0).

44 Estimates of annual numbers of Aboriginal and Torres Strait Islander births in Australia are available from two collections:

• ABS Birth Registrations: this release is based on the registration of births with the Registrar of Births, Deaths and Marriages in each state and territory; and
• Australian Institute of Health and Welfare (AIHW) National Perinatal Epidemiology and Statistics Unit perinatal statistics series: these data are primarily about babies born in hospitals and their mothers (see online Appendix: Differences Between Collections for more information).

45 Alternatively, it is also possible to derive indirect estimates and projections of numbers of Aboriginal and Torres Strait Islander births, based on 2011 Census-based Aboriginal and Torres Strait Islander population estimates:

• For 30 June 2001 to 30 June 2010, estimates of the Aboriginal and Torres Strait Islander population were derived from the Aboriginal and Torres Strait Islander resident population as at 30 June 2011 using a reverse survival technique based on Aboriginal and Torres Strait Islander life tables (see Estimates and Projections, Aboriginal and Torres Strait Islander Australians, 2001 to 2026 (cat. no. 3238.0)). Indirect estimates of Aboriginal and Torres Strait Islander births can then be derived using the number of Aboriginal and Torres Strait Islander children aged 0 at 30 June of each year.
• For 30 June 2012 to 30 June 2026, projections of the Aboriginal and Torres Strait Islander population were derived from the Aboriginal and Torres Strait Islander resident population as at 30 June 2011 using assumptions on future levels of Aboriginal and Torres Strait Islander fertility, mortality and migration. Numbers of projected Aboriginal and Torres Strait Islander births were derived by applying assumed fertility rates to the Aboriginal and Torres Strait Islander female population aged 15-49 years at 30 June of each year (see Estimates and Projections, Aboriginal and Torres Strait Islander Australians, 2001 to 2026 (cat. no. 3238.0)).

Edits and imputations

46 During editing processes for the Birth Registrations collection, some items are corrected where they conflict with other known information. Missing data for some data items are imputed when appropriate. In 2013, there were 1,127 birth registrations for which place of usual residence was imputed, and 24 registrations for which sex was not reported and was imputed.


Parity (previous children of mother)

47 Parity refers to the number of (live) births that a woman has had. Birth order refers to whether a birth is the first, second, third or higher-order birth of the parent. In registering births, information is collected on the number of previous children born to a mother.

48 Changes in ABS processing of birth registrations from 2007 have resulted in the availability of improved information on previous births to mothers. Prior to 2007, the ABS published information on previous births of the mother from the current relationship only, for all states and territories. From 2007 onwards, data on previous births for all relationships (both current and previous, if any) of the mother have been collected for all states and territories, excluding Victoria and Queensland. As a result of these inconsistencies, Australian parity figures in this release exclude data for Victoria, Queensland. Data for Tasmania is also excluded but for the reasons explained in Explanatory Note 34 above.

49 These data are collected as a result of the demand for parity data for analysis and dissemination. For more information on the use of parity data and collection methods associated with these statistics, see Corr, P. and Kippen, R. 2006, The Case for Parity and Birth-Order Statistics, Australia and New Zealand Journal of Statistics, vol. 48, no. 2, pp. 171-200.

50 As a result of the above changes, data on previous births for 2007 onwards are not comparable with data for earlier years. However, the improved information indicates that the prevalence of first births (that is, mothers with no previous children) was overestimated prior to 2007, while numbers of mothers with two or more previous children were underestimated.

Previous children of the mother, Australia(a) - 2006 to 2013
	None	One	Two	Three	Four	Five or more	Total(b)
Year of registration(c)	%	%	%	%	%	%	%
2006	46.7	31.6	12.6	3.8	1.1	0.7	100.0
2007	41.8	32.5	15.1	5.3	2.1	1.3	100.0
2008	42.3	33.0	15.3	5.7	2.2	1.4	100.0
2009	43.3	33.2	14.7	5.3	2.1	1.3	100.0
2010	43.3	33.3	14.8	5.2	2.1	1.3	100.0
2011	43.8	33.4	14.6	4.9	2.0	1.3	100.0
2012	44.4	33.4	14.3	4.9	1.9	1.2	100.0
2013	44.7	33.5	14.1	4.8	1.9	1.1	100.0
(a) Excludes births registered in Victoria, Queensland and Tasmania.
(b) Includes births where previous children of the mother is not stated.
(c) Data for 2006 are the number of previous births of the mother from the current relationship. Data for 2007 onwards are previous births of the mother for all relationships.

Age of parent(s)

51 During birth registration processing since 2007, discrepancies were identified between age of mother data and age of mother derived from date of birth of mother as provided to the ABS by the Registrars. In 2013, there were 197 records (0.06% of all confinements) for which the derived age of mother was found to be inconsistent with the reported age. For these records, the derived age of mother was used. The same process was applied to information on age of father, for which 218 records were affected. For years prior to 2007, median age may have been overstated.

CONFIDENTIALITY

52 The Census and Statistics Act 1905 provides the authority for the ABS to collect statistical information, and requires that statistical output shall not be published or disseminated in a manner that is likely to enable the identification of a particular person or organisation. This requirement means that the ABS must take care and make assurances that any statistical information about individual respondents cannot be derived from published data.

53 Where necessary, tables in this release have had small values suppressed or randomised to protect confidentiality. As a result, sums of components may not add exactly to totals.


ROUNDING

54 Calculations as shown in the commentary sections of this release are based on unrounded figures. Calculations using rounded figures may differ from those released. Where figures have been rounded in tables, discrepancies may occur between sums of component items and totals.

55 Every effort is made to minimise error by working closely with data providers, the careful design of forms, training of processing staff, and efficient data processing procedures.


ACKNOWLEDGEMENTS

56 The ABS' releases draw extensively on information provided freely by individuals, businesses, governments and other organisations. The efforts of each state and territory's Registry of Births, Deaths and Marriages to improve the data quality, coverage and timeliness of birth registration information, processes and systems are noted and valued by the ABS. Their continued cooperation is very much appreciated; without it, the wide range of statistics published by the ABS would not be available. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act 1905.


ADDITIONAL STATISTICS AVAILABLE

57 ABS products and publications are available free of charge from the ABS website <https://www.abs.gov.au>. Click on Statistics to gain access to the full range of ABS statistical or reference information.

58 As well as the statistics included in this and related releases, the ABS may have other relevant data available on request. Inquiries should be made to the National Information and Referral Service on 1300 135 070.

59 The ABS also issues a daily Release Advice on the website which details the products to be released in the week ahead.

60 Other publications which may be of interest to users include Australia's Mothers and Babies, 2011, Australian Institute of Health and Welfare National Perinatal Statistics Unit, AIHW website <www.aihw.gov.au>. Please note there are differences between the ABS and AIHW birth collections; these are discussed in Appendix: Differences Between Collections included with this release on the ABS website.