National Core Maternity Indicators

Note: For reporting purposes, the terms 'females' and 'women' are used interchangeably.

Tobacco smoking during pregnancy

• The smoking indicator has been calculated differently in reports of the National Core Maternity Indicators released from 2020. The current methodology provides a more accurate measure and aligns with the methodology used in the Australia’s mothers and babies reports, which also uses data from the National Perinatal Data Collection. Data for all years has been updated to reflect the improved methodology.
• For smoking in the first 20 weeks of pregnancy for all women giving birth, calculation of the denominator includes the number of women who gave birth with a known smoking status in the first 20 weeks of pregnancy.
• For smoking after the first 20 weeks of pregnancy for all women who gave birth and reported smoking during pregnancy, calculation of the numerator includes women who reported smoking in the first 20 weeks of pregnancy and after the first 20 weeks of pregnancy. Calculation of the denominator includes women who reported smoking in the first 20 weeks of pregnancy.

Antenatal care in the first trimester

• The indicator 'Antenatal care visits in the first trimester for all women giving birth' has been calculated differently in reports of the National Core Maternity Indicators released from 2021. The current methodology provides a more accurate measure and aligns with the methodology used in the Australia’s mothers and babies reports, which also uses data from the National Perinatal Data Collection. Data for all years has been updated to reflect the improved methodology.
• Calculation of the denominator includes women with a stated first antenatal visit in the valid range. The valid range for pregnancy duration at first antenatal visit is 3 to 46 weeks, and women with no antenatal care during pregnancy. Records with missing or invalid data for gestational age at first antenatal visit are excluded.

Vaginal birth after caesarean section

The indicator ‘Women having their second birth vaginally whose first birth was by caesarean section’ has been calculated differently in reports of the National Core Maternity Indicators released from 2021. The indicator was updated in 2021 to only include women whose second birth was a singleton birth. This methodology aligns with the indicator specification (METEOR 785346). Data for all years has been updated to reflect the updated methodology.

Selected women

• In 2022, the selected women criteria were updated to revise the gestational age at birth range to between 37 and 40 completed weeks gestation (previously between 37 and 41 completed weeks gestation).
• The following indicators report on selected women:
  • PI 05 Induction of labour for selected females giving birth for the first time.
  • PI 06 Caesarean section for selected females giving birth for the first time.
  • PI 07 Unassisted (non-instrumental) vaginal birth for selected females giving birth for the first time.
  • PI 08 Assisted (instrumental) vaginal birth for selected females giving birth for the first time.
• Selected women may include women with other medical and obstetric complications.
• These indicators have been calculated differently for this report than in reporting of the National Core Maternity Indicators released prior to 2022. This methodology aligns with the National Core Maternity Indicators, 2024 indicator specifications (METEOR 784860). Data for all years has been updated to reflect the updated methodology and may result in statistics that vary from what has previously been reported.

Babies weighing less than the third centile for gestational age and sex

• In 2024, PI 10 Small babies among births at or after 40 weeks gestation, was updated to a two-part indicator using revised methodology:
  • PI 10a Babies weighing less than the third centile among births at or after 40 weeks gestation
  • PI 10b Babies born at or after 40 weeks gestation among babies weighing less than the third centile.
• Indicator PI 10 aims to identify severe fetal growth restriction (FGR). Previously, a birthweight of less than 2,750 grams after 40 weeks gestation was used as an indication of severe FGR. However, birthweight varies with sex and gestational age. The updated methodology defines severe FGR as a birthweight less than the third centile for gestational age and sex, to more accurately identify babies with severe FGR. The updated methodology also introduces an upper gestational age cut-off of 43 weeks, to align with the availability of birthweight centile data, which excludes a very small number of babies born at 44 or more weeks gestation. For more details, refer to the METEOR specifications. The updated methodology results in an increased proportion of babies identified as having severe FGR, and therefore data are not comparable to previously published data.
• The proportion of babies born at or after 40 weeks gestation among babies weighing less than the third centile, was introduced as a second part of the indicator.

Data presented by sub-populations

In 2024, the methodology used for deriving sub-populations from Australian Bureau of Statistics (ABS) Australian Statistical Geography Standard (ASGS) area of usual residence was updated to exclude mothers whose state or territory of residence was ‘Non-Australian resident’, ‘Not stated’, or ‘Other Territories’ for the purposes of trend data. This aligns with the methodology used in the Australia’s mothers and babies reports, which also uses data from the National Perinatal Data Collection. Data for all years has been updated to reflect the updated methodology and may result in statistics that vary from what has previously been reported. For more information, see Notes for analysis by sub-populations.