Important notes on the data used in this report
The draft National Core Maternity Indicator 18 – ‘Caesarean sections <39 completed weeks (273 days) without obstetric or medical indication’ – was created to benchmark practice and to reduce neonatal respiratory morbidity by minimising early birth. However, this indicator has not yet been submitted for endorsement by the National Health Data and Information Standards Committee. While the indicator was developed by the Expert Commentary Group responsible for the National Core Maternity Indicators, it was not further tested for reporting because the data were not available, and it is not currently reported by the Australian Institute of Health and Welfare (AIHW).
There are a number of limitations with the data quality for one of the data elements: ‘main reason for caesarean section’. This data element is new to the National Perinatal Data Collection, and data that meet its specification are only available for some states and territories. Of the reporting states, data collection processes may be at different stages of maturity, so rates are not comparable across states/territories. For this reason, the reporting states/territories have not been identified.
In addition, state health departments that reviewed their data found that recording of the main reason for caesarean section was not always updated as the clinical situation evolved. For example, medical indications for early birth, such as foetal compromise, were not always recorded as the main indication for early caesarean section if a caesarean section had already been planned for other reasons. Similarly, clinical events such as pre-labour rupture of membranes may lead to an unplanned early caesarean section, but these were not always recorded if the caesarean section had already been planned for other reasons. Data on the original planned date are not available in these cases, and a proportion are likely to have been planned for 39 weeks. This means that the count of planned caesarean sections performed before 39 weeks without medical or obstetric indication is an overestimate for some states. For example, data from one state/territory are overestimated by approximately 3%; another state/territory was unable to distinguish between the main and additional reasons for caesarean section. In this instance, the reason reported as the main reason is the first-listed reason. Another state/territory was unable to collect data for this item (main reason for caesarean section) according to revised specifications introduced from 1 July 2015. Data were mapped by the AIHW to the revised specifications, where possible, and remaining data have been included in the ‘Other, not further defined’ category.
Data on the main indication for caesarean section are published at the state and territory level in the supplementary tables for the AIHW report Australia’s Mothers and Babies. It is anticipated that, as clinicians start to use the data for quality improvement purposes, more states and territories will be able to report according to the specifications.
The numerator of the indicator contains caesarean sections ‘without obstetric/medical indication’ where the caesarean section occurred in the absence of labour and at less than 39 completed weeks for the following reasons:
- Maternal choice in the absence of any obstetric, medical, surgical or psychological indication
- Previous caesarean section
- Previous severe perineal trauma
- Previous shoulder dystocia.
While these may be indications for planned caesarean section, they were not considered reasons for early planned caesarean section – that is, before 39 weeks.
The denominator is the total number of women who gave birth by caesarean section at less than 39 completed weeks’ gestation and where there was no established labour.
Data source and subanalyses
Data are sourced from the National Perinatal Data Collection, which includes births that occur in hospitals, birth centres and the community (such as home births), for public and private patients. Because of small numbers, data are reported only at state/territory level. Reporting by smaller geographical area, remoteness and socioeconomic disadvantage is not possible.
Data of sufficient quality for publication were available from four states/territories. Data on ‘main reason for caesarean section’ did not meet the specification for the remaining four states and territories. The states/territories with publishable data are leaders in data usage for exploring this issue; the other states and territories are developing their capabilities in this area.
Nationally, there were 36,757 caesarean sections before 39 weeks’ gestation without established labour (denominator of the indicator) in 2015. Of these, 15,236 caesarean sections (41%) were from the four reporting states/territories; 21,521 (59%) were from other states and territories, and are not included in the data for this item.