Data quality, availability and interpretation

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

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 2018. The vast majority of all babies (97.1%) had the same Indigenous status as their mother while only a small proportion had a different Indigenous status recorded (2.9%). However, of the 17,263 babies reported as Indigenous in the NPDC in 2018 (5.7% of all babies), one-quarter (25%) were born to non-Indigenous mothers.

Table 1: Births, by Indigenous status of the baby and mother, 2018

Indigenous status of the mother

Indigenous baby

Non-Indigenous baby

Not stated baby

Total

Indigenous mother

12,921

(4.3%)

940

(0.3%)

101

(0.0%)

13,962

(4.6%)

Non-Indigenous mother

4,328

(1.4%)

280,922

(92.7%)

3,099

(1.0%)

288,349

(95.2%)

Not stated mother

14

(0.0%)

444

(0.1%)

260

(0.1%)

718

(0.2%)

Total

17,263

(5.7%)

282,306

(93.2%)

3,460

(1.1%)

303,029

(100.0%)

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
  • data are not currently supplied by a state and territory for the NPDC (data items that are not part of the Perinatal NMDS are not mandatory for provision to the NPDC).

These exclusions are summarised in Table 2, and are also noted throughout the report where applicable. These exclusions apply to both the numerator and denominator for rate calculations, and the data presented are not representative of the jurisdictions excluded.

Table 2: Summary of state and territory exclusions in 2018, by topic

Topic Exclusion
Number of antenatal visits Victoria (excluded from trend analysis only due to data not being available for all years)
Hypertension and diabetes(a) Victoria (data not currently available according to specifications)
Resuscitation(a) Western Australia (data not provided)
Hospital length of stay (baby) Western Australia (data not provided on baby's mode of separation(a) from the birth hospital which is required for analysis of this topic)
Admission to special care nursery/ neonatal intensive care unit(a) Western Australia and New South Wales (data not provided)

Note:
(a) These data items are not currently part of the Perinatal NMDS and are not mandated for provision to the NPDC.

Detailed information on completeness for all data items used in the data visualisations is available in the interactive data visualisation below at the national level for 2017. Note that this includes jurisdictions that provided data only.

Definitions for the terms used to quantify completeness:

  • Stated: proportion of appropriate values supplied for the data item during the specified collection year.
  • Not stated: proportion of values supplied as not stated or missing, during the specified collection year.

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 14.5% in 2018.

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.