National Core Maternity Indicators

Data source: National Perinatal Data Collection

The data used for the National Core Maternity Indicators is sourced from the National Perinatal Data Collection (NPDC).

The NPDC is a national population-based cross-sectional collection of data on pregnancy and childbirth. The data are based on births reported to the perinatal data collection in each state and territory in Australia. Midwives and other birth attendants, using information obtained from mothers and from hospital or other records, complete notification forms for each birth. A standard de-identified extract is provided to the Australian Institute of Health and Welfare (AIHW) on an annual basis to form the NPDC.

More information about the NPDC can be found at National Perinatal Data Collection and National Perinatal Data Collection data availability resource.

Data quality

The NPDC consists of the Perinatal National Minimum Data Set (NMDS) and some additional data items. The Perinatal NMDS uses agreed standards for data collection and regular reviews of compliance are conducted across all jurisdictions. Changes to all NMDSs are applied on a financial year basis from 1 July each year. Disaggregation and historical reporting of some indicators rely to an extent on non-NMDS data items, which are provided by jurisdictions on a voluntary basis and may be affected by differences in collection practices. For more information see the NPDC data quality statement.

Due to data editing, subsequent updates of state and territory databases, and differences in scope for inclusion, the numbers may differ slightly from those published by the states and territories or other reporting.

Some data quality issues are specific to the NCMIs rather than the NPDC as a whole. Information is not available from all jurisdictions to support the 13 indicators in all years. An overview of data availability for reporting against relevant indicators is provided in Table 5. When a jurisdiction’s data are missing, the national result can be affected. The effect is more pronounced if the population in the missing jurisdiction is large or when the jurisdictional result is very different to the national result. When data for a jurisdiction are missing, it can also affect other disaggregation categories. For instance, a jurisdiction like the Northern Territory has a relatively high proportion of First Nations mothers and mothers who live in Very remote areas. Subtotals for First Nations mothers and mothers who live in Very remote areas would be disproportionately affected if data from the Northern Territory were not available.

When Victoria supplied 2009 and 2010 data to the NPDC, legislation prevented the supply of data except Perinatal NMDS items, meaning that some NCMIs could not be calculated for Victoria for these years. In 2015, following a change in legislation, Victoria resupplied data for 2010 and 2011. This included supply of non-NMDS items as well as updates to previously supplied data with enhanced data quality following completion of the implementation of their electronic transfer of data system. There are no remaining issues with the supply of Victorian data for 2010 and 2011, though the data in this report may differ from the provisional data reported previously by the AIHW in other publications.

In the data supplied from Tasmania prior to 2013, presentation at birth for caesarean sections births was not reported by hospitals using paper-based forms. Presentation at birth for caesarean sections births was included in the paper-based form from the 1 January 2013. As a result, Tasmania can only be reported in indicators that use presentation at birth in their definition from 2013 onwards.

From 2014, data item ‘Caesarean section at most recent previous birth indicator’ (METEOR 422187) was introduced into the Perinatal NMDS. Although not an NMDS item prior to 2014, data collected into the NPDC using the data element ‘Caesarean section indicator (last previous birth)’ (METEOR 301993) is used in the indicator definition of ‘Women having their second birth vaginally whose first birth was by caesarean section’ from 2007 to 2013. As a result, data from Victoria were not available in 2007 to 2009, or Western Australia in 2013.

At the time of writing, data items ‘Tobacco smoking in the first 20 weeks of pregnancy’ and ‘Tobacco smoking after 20 weeks of pregnancy’ were not available for NSW for use in national reporting for the years 2021 to 2022.

At the time of writing, the ACT had only provided partial data for 2022 due to a major change in the collection of ACT’s health data, implemented in early November 2022. To enable national reporting of 2022 data on mothers and babies, the AIHW have constructed a dataset using complete 2022 data for 7 jurisdictions and a compilation of data for the ACT. The ACT’s data consists of their 2022 data for January to October, supplemented by their 2021 data for November and December.

As 2023 was the first full year of data extracted from ACT’s new digital health system, some of ACT’s data for 2023 are currently unavailable or may not have complete coverage. At the time of writing, data items ‘Tobacco smoking in the first 20 weeks of pregnancy’, ‘Tobacco smoking after 20 weeks of pregnancy’, ‘Gestation at first antenatal visit’, and ‘General anaesthesia for operative delivery’ were not available for ACT for 2023.

At the time of writing, data for indicators PI14a–d were not available for South Australia.