Data source and quality


State and territory health departments are thanked for their contribution to the National Perinatal Data Collection and their review of information. The authors also gratefully acknowledge the clinical advice and input of the expert reviewers:

  • Professor Michael Humphrey AM, Perinatal Adviser to AIHW, Chair National Maternal and Perinatal Mortality Advisory Group, Adjunct Professor, James Cook University
  • Professor Caroline Homer AO, Co-Program Director Maternal, Child and Adolescent Health, Burnet Institute and Honorary Emeritus Professor of Midwifery, Faculty of Health, University of Technology Sydney 
  • Dr Janet Hornbuckle, Maternal Fetal Medicine Specialist, King Edward Memorial Hospital, Western Australia and Clinical Senior Lecturer in Obstetrics & Gynaecology, University Western Australia

The AIHW acknowledges funding provided by the Australian Government Department of Health as part of the National Maternity Data Development Project (NMDDP).

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 National Perinatal Data Collection.

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. With the exception of two indicators (Apgar score and small babies at term), the indicator definitions rely to some extent on non-NMDS data items, which are provided by jurisdictions on a voluntary basis and may be affected by differences in collection practices.

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 12 indicators in all years. An overview of data availability for reporting against relevant indicators is provided in Table 2. When a jurisdictions 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 effect other disaggregation. For instance, a jurisdiction like the Northern Territory has a relatively high proportion of mothers who live in Very remote areas and who are Indigenous. Subtotals for mothers who live in Very remote areas and Indigenous mothers 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 (ETOD) 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/DSS 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.

Table 2: Jurisdictions for which perinatal data were not available for reporting the NCMIs, 2004–2019
  Indicator Jurisdiction and years data not available
PI 05 Induction of labour for selected women giving birth for the first time

Tasmania 2004 to 2012

Victoria 2009

PI 06 Caesarean section for selected women giving birth for the first time

Tasmania 2004 to 2012

Victoria 2009

PI 07 Non-instrumental vaginal birth for selected women giving birth for the first time

Tasmania 2004 to 2012

Victoria 2009

PI 08 Instrumental vaginal birth for selected women giving birth for the first time

Tasmania 2004 to 2012

Victoria 2009

PI 03

Episiotomy for women having their first baby and giving birth vaginally

  1. without instruments to assist the birth
  2. assisted with instruments

Victoria 2009

PI 09 General anaesthetic for women giving birth by caesarean section

Victoria 2009 and 2010

PI 15 Women having their second birth vaginally whose first birth was by caesarean section

Victoria 2007 to 2009

Western Australia 2013