Data quality and availability

Data availability

Some topics in this report may exclude data for selected states and territories for reasons including:

  • changes in definitions or data collection methods in a state and territory that mean the data item is not comparable over time (trend analyses only)
  • data are not currently collected by a state and territory, or are not collected in a format that is comparable with the specifications for the NPDC, NPMDC or the NMMDC
  • data are not currently supplied by a state and territory for the NPDC, NPMDC or NMMDC. Data items that are not part of the Perinatal NMDS are not mandatory for provision to the NPDC, and there are currently no Perinatal NMDS items in the NPMDC.

NPDC, NPMDC and NMMDC exclusions are noted in footnotes under data visualisations, and are also available in the accompanying data tables. These exclusions apply to both the numerator and denominator for rate calculations, and the data presented are not representative of the jurisdictions excluded.

Detailed information on completeness for all NPDC data items used in the web report and data visualisations is available in the National Perinatal Data Collection data availability resource interactive data visualisation tool. Note that this includes jurisdictions that provided data only.

National Perinatal Data Collection

Detailed information on completeness, accuracy and other aspects of data quality for the National Perinatal Data Collection (NPDC) is in the data quality statement.

Tabulated data in this report are based on births in each state and territory in 2018 that meet the criteria for inclusion in the Perinatal NMDS. Due to data editing, subsequent updates of state and territory databases, and differences in scope for inclusion, the numbers may differ slightly from those in reports published by the states and territories.

Unless otherwise stated, the data in this report and related supplementary tables relate to the state or territory where births occurred in 2019 rather than to the state or territory of usual residence of the mother.

Due to rounding, percentage totals may not add to 100 and subtotals may not sum to the percentages for the categories.

Terminology

The terms ‘mothers’ or ‘women who gave birth’ have been used when referring to maternal characteristics, whereas ‘births’ refers to babies.

Quality of data for reporting Indigenous status

Indigenous status is a measure of whether a person identifies as being of Aboriginal and/or Torres Strait Islander origin. Indigenous status of the mother has been a mandatory data item for the Perinatal NMDS since its inception in 1997. Indigenous status of the baby was also added to the NMDS for collection for the first time in the 2012–13 reference year (from 1 July 2012).

This item, when used in conjunction with the mother’s Indigenous status, is a better baseline measure of health for all Indigenous children. However, the outcomes of babies of Indigenous mothers remain a key data resource for assessing antenatal care in pregnancy and other interventions before or during pregnancy, aimed at improving the health of mothers and babies.

Unless otherwise stated, data for babies are based on the Indigenous status of the mother.

Table 1 shows the relationship between Indigenous status of the mother and Indigenous status of the baby in 2019. The vast majority of all babies (96.6%) had the same Indigenous status as their mother while only a small proportion had a different Indigenous status recorded (3.3%). However, of the 18,086 babies reported as Indigenous in the NPDC in 2019 (6.0% of all babies), over one-quarter (26%) were born to non-Indigenous mothers.

Table 1: Births, by Indigenous status of the baby and mother, 2019

Indigenous status of the mother

Indigenous baby

Non-Indigenous baby

Not stated baby

Total

Indigenous mother

13,289

( 4.4%)

1,053

( 0.3%)

125

( 0.0%)

14,467

( 4.8%)

Non-Indigenous mother

4,782

( 1.6%)

279,232

( 92.1%)

2,878

( 0.9%)

286,892

( 94.7%)

Not stated mother

15

( 0.0%)

1,410

( 0.5%)

270

( 0.1%)

1,695

( 0.6%)

Total

18,086

( 6.0%)

281,695

( 93.0%)

3,273

( 1.1%)

303,054

(100.0%)

 

Australian Capital Territory births

The Australian Capital Territory data contain a relatively high proportion of New South Wales residents who gave birth in the Australian Capital Territory. The proportion of mothers who gave birth in the Australian Capital Territory who were residents elsewhere was 14.0% in 2019.

When interpreting the data, it is important to note that these births to non-residents may include a disproportionate number of high-risk and multi-fetal pregnancies associated with poorer perinatal outcomes. This is because women with high risk pregnancies may be more likely to be transferred from smaller centres in New South Wales (that do not have the facilities to manage such births safely) to the Australian Capital Territory to give birth.

Therefore, percentages or rates such as those for pre-term births and perinatal deaths may be inflated for births that occur in the Australian Capital Territory. Reporting by state or territory of usual residence of the mother helps to address this issue.

National Maternal Mortality Data Collection

Detailed information on completeness for all data items in the NMMDC at the national level, for 2012 to 2019, is available in the interactive data visualisation below.

Definitions for the terms used to quantify completeness:

Supplied: supplied an appropriate value for a proportion of records for the data item during specified collection year/s

Not supplied or stated: proportion of values supplied as not stated or missing, where a jurisdiction has either supplied appropriate values for a portion of records or did not supply any value for all records for the data item during the specified collection year/s.

Due to its health and privacy legislation, only limited summary data on maternal deaths from 2006–2018 were supplied by Western Australia. As these data provided are already aggregated, rather than provided by case, they cannot be included in the NMMDC so have not been included in the data visualisation below, but are included in analysis where possible.

The data visualisation shows a bar chart of the availability of data items in the National Maternal Mortality Data Collection for the period 2012 to 2019.

Visualisation not available for printing

National Perinatal Mortality Data Collection

Detailed information on completeness for all data items in the NPMDC is available, at the national level, in the interactive data visualisation below for 2013 to 2019.

Definitions for the terms used to quantify completeness:

Supplied: supplied an appropriate value for a proportion of records for the data item during specified collection year/s

Not supplied or stated: proportion of values supplied as not stated or missing, where a jurisdiction has either supplied appropriate values for a portion of records or did not supply any value for all records for the data item during the specified collection year/s.

The data visualisation shows a bar chart of the availability of data items in the National Perinatal Mortality Data Collection for the period 2013 to 2019.

Visualisation not available for printing

Preliminary data on perinatal deaths

Preliminary data on perinatal deaths covered in this web report is from the National Perinatal Data Collection. The AIHW established the separate, enduring National Perinatal Mortality Data Collection to obtain complete information on these deaths.

Data on stillbirths and neonatal deaths are provided to the NPDC by jurisdictions as a subset of the larger cohort of all babies born in the same collection period. These preliminary data on stillbirths and neonatal deaths are made available to the public approximately 18 months after the end of the collection period.

Because these data are supplied to the AIHW often prior to completion of all Jurisdictional Mortality Review Committee reports, the data is not as comprehensive as that supplied to the NPMDC, particularly pertaining to PSANZ classification regarding the cause of death and contributory factors.

These preliminary data may also not include neonatal deaths for babies transferred to another hospital, re-admitted to hospital after discharge or who died at home after discharge.

Data provided to the NPMDC may vary from the preliminary data reported by the NPDC due to a variety of factors. Such factors include the inclusion of babies transferred to another hospital, re-admitted to hospital after discharge or who died at home after discharge; or cases where not enough detail was able to be provided by the jurisdiction to enable linkage of a particular death in the NPMDC back to the corresponding record in the NPDC.

Quality of data for reporting Indigenous status

Indigenous status is a measure of whether a person identifies as being of Aboriginal and/or Torres Strait Islander origin. Unless otherwise stated, data for babies are based on the Indigenous status of the mother. However, the outcomes of babies of Indigenous women remain a key data resource for assessing provision of antenatal care in pregnancy and other interventions before or during pregnancy.

Comparing NPMDC data with Victorian Consultative Council on Obstetric and Paediatric Mortality and Morbidity data

The stillbirth data for Victoria reported to the National Perinatal Mortality Data Collection differs to that reported by the Victorian Consultative Council on Obstetric and Paediatric Mortality and Morbidity (CCOPMM). For 2019, the CCOPMM annual report shows 508 stillbirths and an adjusted stillbirth rate of 6.4 per 1,000 births (CCOPMM 2021. Victoria’s Mothers Babies and Children 2019. Melbourne: Victorian Government). The difference is due to the following exclusions applied to the stillbirths reported by CCOPMM:

  • Stillbirths resulting from terminations of pregnancy for psychosocial indications
  • Stillbirths proven to have occurred at less than 20 weeks’ gestation (for example, where a fetal death in utero diagnosed by ultrasound at 19 weeks’ gestation), but where birth occurs at 20 weeks’ gestation or more
  • Stillbirths where a fetal death in utero is diagnosed at 20 weeks’ gestation or more, but where the birthweight is less than 150 grams.

Comparing NPMDC data with ABS registrations of death data

Perinatal death data reported by the Australian Bureau of Statistics (ABS) are not directly comparable with the NPMDC and NPDC data contained in this report. Variation in the number of perinatal deaths reported by the ABS and NPMDC can be seen in the table below.

While the definitions of stillbirth (fetal death in ABS reporting) and neonatal death are the same, ABS data are sourced from state and territory registrars of Births, Deaths and Marriages. Data from the NPMDC and NPDC contained in this report are sourced from midwives, and other staff, who collect information from mothers and perinatal administrative and clinical record systems.

It is the responsibility of the parents to register a birth with Births, Deaths and Marriages, however some perinatal deaths may not be recorded when notifications are not registered by the parents. A delay in registrations is often seen, particularly for stillbirths, with the original date of death often being many years prior to the date of registration. This means the accuracy of the number of perinatal deaths reported by the ABS for a particular year often improves over time.

Table 1: Number of perinatal deaths reported by Australian Bureau of Statistics and the National Perinatal Mortality Data Collection, Australia, 2013–2019
Year NPMDC Stillbirths ABS Stillbirths NPMDC Neonatal deaths ABS Neonatal deaths
2013 2,194 1,781 822 763
2014 2,225 1,698 796 714
2015 2,149 1,718 688 707
2016 2,114 1,724 751 700
2017 2,174 1,760 800 744
2018 2,116 1,682 718 737
2019 2,183 1,686 714 727

 

Note: ABS stillbirths and neonatal deaths are reported by the year in which the death occurred (ABS 2019, Customised report).

For more information on perinatal deaths data collected by the ABS, visit the perinatal deaths page at the Australian Bureau of Statistics.