EXPLANATORY NOTES


INTRODUCTION

1 This publication contains statistics on perinatal deaths for Australia, 2008.

2 Perinatal deaths comprise all fetal deaths (of at least 20 weeks gestation or at least 400 grams birth weight), and all neonatal deaths (all live born babies who die within 28 completed days of birth, regardless of gestation or birth weight). Fetal deaths are only included in the perinatal deaths collection. However, neonatal deaths are included in both the perinatal deaths and the causes of death collections.

3 The Explanatory Notes and Technical Notes in this publication should be read in conjunction with the Explanatory Notes and Technical Notes in Causes of Death, Australia, 2008 (3303.0).

4 In order to complete a perinatal death registration, the death must be certified by either a doctor using the Certificate of Cause of Perinatal Death or by a coroner. For 2008, 96% of perinatal deaths were certified by a doctor. The remaining 4% were reported to a coroner.

5 The registration of deaths is the responsibility of the eight individual state and territory Registrars of Births, Deaths and Marriages. As part of the registration process, information about the cause of death is supplied by the medical practitioner certifying the death or by a coroner. The information is provided to the Australian Bureau of Statistics (ABS) by individual Registrars for coding and compilation into aggregate statistics. In addition, the ABS supplements this data with information from the National Coroners Information System (NCIS). For further information on how the ABS obtains cause of death information, see Causes of Death, Australia, 2008 Explanatory Notes 2-3 (cat. no. 3303.0).

6 The data presented in this publication are also included in a series of data cubes that are available on the ABS website.

7 A Glossary is also provided which details definitions of terminology used.


2008 SCOPE AND COVERAGE

8 The statistics in this publication relate to the number of perinatal deaths registered, not those which actually occurred, in the years shown.


Scope of perinatal death statistics

9 The ABS perinatal deaths collection includes all perinatal deaths that occurred and were registered in Australia. Deaths of Australian residents that occurred outside Australia may be registered by individual Registrars, but are not included in ABS deaths or perinatal deaths statistics.

10 The scope of the perinatal death statistics includes all fetal deaths (at least 20 weeks gestation or at least 400 grams birth weight) and neonatal deaths (all live born babies who die within 28 completed days of birth, regardless of gestation or birth weight). This scope was adopted for the 2007 perinatal deaths collection, and was applied to historical data for 1999 to 2006. For more information on the changes in scope rules see Perinatal Deaths, Australia, 2007 Explanatory Notes 18-20 (cat. no. 3304.0).

11 The scope of perinatal death statistics includes:

• all deaths being registered for the first time;
• deaths in Australia of temporary visitors to Australia;
• deaths occurring within Australian Territorial waters;
• deaths occurring in Australian Antarctic Territories or other external territories (excluding Norfolk Island);
• deaths occurring in transit (i.e. on ships or planes) if registered in the State of 'next port of call';
• deaths of Australian Nationals overseas who were employed at Australian legations and consular offices (i.e. deaths of Australian diplomats while overseas) where able to be identified; and
• deaths that occurred in earlier reference periods that have not been previously registered (late registrations).

12 The scope of the statistics excludes:

• repatriation of human remains where the death occurred overseas; and
• deaths occurring on Norfolk Island.

13 Fetal deaths are registered only as a death, they are not in scope of either the Births, Australia (cat. no. 3301.0) or Deaths, Australia (3302.0) collections. Neonatal deaths are registered first as a birth and then as a death and are in scope of both the Births and Deaths collections.

14 For 1996 and previous editions of this publication, data relating to perinatal deaths were based upon the World Health Organization (WHO) recommended definition for compiling national perinatal statistics. The WHO definition of perinatal deaths included all infants, and those fetuses weighing at least 500 grams or having a gestational age of at least 22 weeks or body length of 25 centimetres crown-heel. A summary table based on the WHO definition of perinatal deaths (all infants, and those fetuses weighing at least 500 grams or having a gestational age of at least 22 weeks) is included in this release (see data cube 4).


Coverage of Perinatal Death Statistics

15 Ideally, for compiling annual time series, the number of events (deaths) should be recorded and reported as those occurring within a given reference period such as a calendar year. However, due to lags in registration of events (and/or processing and data transfer lags) there can be delays in the provision of information to the ABS, and not all deaths are registered in the year that they occur.

16 In effect there are 3 dates attributable to each death:

• the date of occurrence (of the death);
• the date of registration or inclusion on the State/Territory register; and
• the month in which the registered event is lodged with the ABS.

17 Approximately 10% to 13% of perinatal deaths occurring in one year are not registered until the following year or later. These are included with the count of registered perinatal deaths published for that year.


2008 CLASSIFICATIONS

18 The following classifications have been applied to the 2008 perinatal deaths collection. Detailed explanations of these classifications can be found in the Explanatory Notes of Causes of Death, Australia, 2008 (3303.0):

• Indigenous Status
• Australian Standard Geographical Classification (ASGC)
• Standard Australian Classification of Countries (SACC)
• International Classification of Disease (ICD)

2008 MORTALITY CODING

19 For perinatal deaths, both the main condition in the fetus/infant, and the main condition in the mother are coded to the full four-digit level of the tenth revision of ICD. Causes selected for publication in this issue are those categories which were responsible for a significant proportion of perinatal deaths.

20 There is some variability over time across a range of the perinatal death categories and where the numbers are small, caution should be applied in drawing inferences about change over time.

21 For information regarding updates to ICD-10 and automated coding, see Causes of Death, Australia, 2008 Explanatory Notes 34-38 (cat. no. 3303.0).


State and Territory Data

22 Causes of death statistics for states and territories in this publication have been compiled in respect of the state or territory of usual residence of the deceased, regardless of where in Australia the death occurred and was registered. Deaths of overseas usual residents which occur in Australia are included in the state/territory in which their death was registered.

23 Given the small number of perinatal deaths which occur in some states and territories, some data provided on a state/territory basis in this publication have been aggregated for South Australia, Western Australia, Northern Territory and Australian Capital Territory.

24 Data presented in this publication are published on a state or territory of usual residence basis. Statistics compiled on a state or territory of registration basis are available on request.


2008 DATA QUALITY

25 In compiling causes of death statistics, the ABS employs a variety of measures to improve quality, which include:

• providing certifiers with certification booklets for guidance in reporting causes of death on medical certificates. See Information Paper: Certification of Death (cat. no. 1205.0.55.001);
• seeking detailed information from the National Coroners Information System (NCIS); and
• editing checks at the individual record and aggregate levels.

26 For more information on data quality in the cause of death collection, see Explanatory and Technical Notes related to Causes of Death, Australia, 2008 (cat. no. 3303.0).


Indigenous deaths

27 Due to data quality issues and the small number of Indigenous perinatal deaths registered each year, this publication includes the aggregated perinatal deaths statistics for the five year period from 2004 to 2008 reference years for Australia. Because of the data quality issues, more detailed breakdowns of Indigenous deaths are provided only for New South Wales, Queensland, South Australia, Western Australia and the Northern Territory.

28 For information regarding Indigenous deaths data quality see Causes of Death, Australia, 2008 Explanatory Notes 53-62 (cat. no. 3303.0).


Data quality over time

Perintatal data processing system

29 A perinatals component of the Mortality processing system was developed and implemented for the processing of 2008 coroner certified perinatal deaths. This included adding new edits to improve the quality of data and aligning the system more closely with perinatal coding requirements (i.e. ensuring that a mother's condition code is not accepted in the fetus/infant's field, and vice versa).

30 As for previous years, doctor certified perinatal deaths for 2008 were processed manually. This included the coding of underlying and multiple cause data. While data has been quality checked, it is acknowledged that this manual process has introduced an increased risk in data integrity.

Treatment of 'not stated' data in the ABS application of perinatal scope rules in relation to fetal death

31 As all 'live births' are considered in scope of the collection regardless of gestation or birth weight, the increase in 'not stated' data affects the application of scope rules for fetal deaths only.

32 The ABS scope rules include fetal deaths based on gestation of at least 20 weeks or birth weight of at least 400 grams. This scope is consistent with the legislated requirement for all state and territory Registrars of Births, Deaths and Marriages to register all fetal deaths of at least 20 weeks gestation or 400 grams birth weight. Based on this legislative requirement, in the case of missing gestation and/or birth weight data, the fetal record is considered in scope and included in the dataset. A record is only considered out of scope if both gestation and birth weight data are present, and both fall outside the scope criteria (ie 19 weeks or less gestation and 399 grams or less birth weight). This rule has been applied to all perinatal data presented in this publication and was applied to all data (1999-2007) presented in the Perinatal Deaths, Australia, 2007 (cat. no. 3304.0) publication.


SPECIFIC ISSUES FOR 2008 DATA

33 A number of issues should be taken into account by users when analysing the 2008 causes of perinatal death data, as outlined below.


Main and leading condition in the fetus/infant

Other disorders originating in the perinatal period (P90-P96)

34 The number of perinatal deaths with main condition in the fetus/infant of Other disorders originating in the perinatal period (P90-P96) increased by 18% in 2008, to 929 deaths. This was a return to pre-2006 figures.

35 In coding of 2008 data, coroner certified neonatal deaths with no cause of death information were coded to 'Condition originating in the perinatal period, unspecified' (P969) instead of 'Other ill-defined and unspecified causes of mortality' (R99). This serves to capture the information that the record is neonatal.

36 Fetal death of unspecified cause (P95) is used when no other information on a fetal death certificate is supplied. Prior to 2006, this would have been queried in an attempt to assign a more specific code.

37 It should also be noted that an absence of paper forms for the Victorian jurisdiction may be responsible for the increase in records coded to Fetal death of unspecified cause (P95) in that jurisdiction, in the absence of more specific cause of death information.

Disorders related to length of gestation and fetal growth (P05-P08)

38 The number of perinatal deaths with main condition in the fetus/infant of Disorders related to length of gestation and fetal growth (P05-P08) decreased by 11% in 2008, to 773 deaths. The decrease continued the trend since 2006 towards lower counts for these causes, however, these figures were still higher than they were in 2005 and earlier. It is likely that the higher numbers since 2006 are due to the cessation of querying perinatal deaths with doctors. Prior to 2006, deaths listing these causes would have been queried to obtain a more specific cause of death.

Respiratory and cardiovascular disorders specific to the perinatal period (P20-P29)

39 The number of perinatal deaths with main condition in the fetus/infant of Respiratory and cardiovascular disorders specific to the perinatal period (P20-P29) decreased by 27% in 2008, to 163 deaths. This is consistent with a trend in the time series towards lower counts for this cause, with 2008 data the lowest point in the time series.


Main condition in the mother

Fetus and newborn affected by other specified complications of labour and delivery (P038)

40 In 2008, changes in coding practices meant that planned abortions were coded to the mother's condition Fetus and newborn affected by other specified complications of labour and delivery (P038) as well as, instead of solely, to the child's condition Termination of pregnancy, fetus and newborn (P964). The impact of this can be seen in Fetus and newborn affected by other complications of labour and delivery (P03) with an increase of 151% in 2008, to 148 deaths.


BIRTHS DATA

41 Appendix 1 provides details of the number of live births registered which have been used to calculate the fetal, neonatal and perinatal death rates shown in this publication. Appendix 1 also provides data on fetal deaths used in the calculation of fetal and perinatal death rates. These also enable further rates to be calculated.


CONFIDENTIALISATION OF DATA

42 Data cells with small values have been randomly assigned to protect confidentiality. As a result some totals will not equal the sum of their components. It is important to note that cells with 0 values have not been effected by confidentialisation.


EFFECTS OF ROUNDING

43 Where figures have been rounded, discrepancies may occur between totals and sums of the component items.


ACKNOWLEDGEMENT

44 This publication draws extensively on information provided freely by the state and territory Registrars of Births, Deaths and Marriages, and the Victorian Institute of Forensic Medicine who manage the NCIS. Their continued cooperation is very much appreciated: without it, the wide range of vitals statistics published by the ABS would not be available.


RELATED PRODUCTS

45 Other ABS publications which may be of interest are outlined below. Please note, older publications may be available through the state and national libraries. All publications released from 1998 onwards are available on the ABS website <https://www.abs.gov.au>.

ABS Directions in Aboriginal and Torres Strait Islander Statistics, Jun 2007, cat. no. 4700.0
Australian Demographic Statistics, cat no. 3101.0
Australian Social Trends, cat. no. 4102.0
Causes of Death, Australia: Doctor Certified Deaths, Summary Tables, cat. no. 3303.0.55.001
Causes of Infant and Child Deaths, Australia, 1982-96, cat. no. 4398.0
Deaths From External Causes, Australia - 1998 to 2002, cat. no. 3320.0
Experimental Estimates and Projections, Aboriginal and Torres Strait Islander Australians, 1991 to 2021, cat. no. 3238.0
Mortality Atlas, Australia, 1997 to 2000, cat. no. 3318.0
Population Projections, Australia, 2006 to 2101, cat. no. 3222.0
Recent Developments in the Collection of Aboriginal and Torres Strait Islander Health and Welfare Statistics, 2005, cat. no. 4704.0.55.001
The Health and Welfare of Australia's Aboriginal and Torres Strait Islander Peoples, 2008, cat. no. 4704.0

46 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 and reference information. For details on products scheduled for release in the coming week, click on the Future Releases link on the ABS homepage.