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 2021 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 2021, 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.

Quality of data for reporting First Nations status

First Nations status is a measure of whether a person identifies as being of First Nations origin. First Nations status of the mother has been a mandatory data item for the Perinatal NMDS since its inception in 1997. First Nations 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 First Nations status, is a better baseline measure of health for all First Nations children. However, the outcomes of babies of First Nations 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 First Nations status of the mother.

Table 1 shows the relationship between Indigenous status of the mother and Indigenous status of the baby in 2021. Most babies (96%) had the same Indigenous status as their mother while only a small proportion had a different Indigenous status recorded (3.9%). However, of the 19,155 babies reported as First Nations in the NPDC in 2021 (6.1% of all babies), one-quarter (27%) were born to non-Indigenous mothers.

Table 1: Births, by First Nations status of the baby and mother, 2021

First Nations status of the mother

First Nations baby

Non-Indigenous baby

Not stated baby

Total

First Nations mother

14,046

(4.4%)

1,390

(0.4%)

253

(0.1%)

15,689

(5.0%)

Non-Indigenous mother

5,092

(1.6%)

288,928

(91.5%)

4,571

(1.4%)

298,591

(94.6%)

Not stated mother

17

(0.0%)

1,001

(0.3%)

407

(0.1%)

1,425

(0.5%)

Total

19,155

(6.1%)

291,319

(92.3%)

5,231

(1.7%)

315,705

(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 about 15% in 2021.

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

Definitions.

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 not 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.

Western Australia data provision

Due to its health and privacy legislation, only limited summary data on maternal deaths from 2006–2021 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 Figure 1, below. However, they are included in analysis where possible.

Figure 1: Quality and availability of data in the National Maternal Mortality Data Collection

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 2021.

National Perinatal Mortality Data Collection

Detailed information on completeness for all data items in the National Perinatal Mortality Data Collection (NPMDC) is available, at the national level, in the interactive data visualisation below for 2013 to 2019. The addition of data for 2020 and 2021 is planned for 2024.

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 not 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.

Figure 2: Quality and availability of data in the National Perinatal Mortality Data Collection

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 2020.

Preliminary data on perinatal deaths

Preliminary data on perinatal deaths covered in this web report are 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 are not as comprehensive as those 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 First Nations 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 have historically differed to what are reported by the Victorian Consultative Council on Obstetric and Paediatric Mortality and Morbidity (CCOPMM). For example, for 2020, the NPMDC recorded 673 stillbirths and a rate of 8.7 stillbirths per 1,000 births, compared with the CCOPMM annual report that showed 492 stillbirths and an adjusted stillbirth rate of 6.4 per 1,000 births (CCOPMM 2021. Victoria’s Mothers Babies and Children 2020. 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.

At the time of writing, CCOPMM had not published their 2021 data.

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; for example, the number of stillbirths based on the NPMDC is consistently and notably higher than reported by the ABS.

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 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 2: Number of perinatal deaths reported by Australian Bureau of Statistics and the National Perinatal Mortality Data Collection, Australia, 2013–2021
YearNPMDC StillbirthsABS StillbirthsNPMDC Neonatal deathsABS Neonatal deaths
20132,1941,781822763
20142,2251,698796714
20152,1491,718688707
20162,1141,724751700
20172,1741,760800744
20182,1161,682718737
20192,1831,686714727
20202,2731,784731706
20212,2781,700738732

Note: ABS stillbirths and neonatal deaths are reported by the year in which the death occurred (ABS 2023, Causes of Death, Australia).

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