The significance of this study lies in the large sample size and the finding that regardless of the low-risk status of these women the intervention rates such as caesarean section and instrumental birth have continued to rise slowly year after year. These rates do not appear to be parallel to or be associated with a better infant outcome. The NSW rate of perinatal mortality was between 8.6 and 9.6 per 1000 births between 2000 and 2005 and between 8.7 and 9 per 1000 births between 2005 and 200915
. A recent randomised controlled trial of case load midwifery (continuity of carer) for low-risk women compared to standard care offered in a large teaching hospital in Australia found a 22% reduction in caesarean section rate under continuity of midwifery care with no difference in perinatal mortality.17
This indicates that changes in caesarean section rates can occur with little impact on perinatal mortality. The difference between private and public maternity care suggests that the rates are potentially associated with variations in practitioner behaviour as opposed to the poor health of women. Other authors have also asserted that rising caesarean section rates centre on clinician preferences. Leitch and Walker18
stated that while indications for caesarean section have not changed much over time there has been lowering in the overall threshold concerning the decision to carry out a caesarean.
Our study is limited to providing a snapshot view of the birth outcomes in a defined time period. However, this study repeats the analysis of a paper published in 2000 providing the reader with a more detailed picture of the current state of obstetric intervention in NSW. The advantages of using population-based datasets, such as the MDC, include the size of the dataset and the guaranteed accuracy of a validated dataset. The limitations are the restricted number of variables that are included and the scarcity of specific information on potential confounders. Previous validation studies have reported high levels of data accuracy for the majority of diagnoses and procedures conducted during labour and delivery in the state-wide data base,19
although the recording of medical conditions are overall generally underreported.19
While we could not control for obesity due to lack of reliable data, women who have private health insurance have lower rates of obesity and higher socioeconomic status hence these health disadvantages are most likely over-represented in the public women.22
There are also several other sociodemographic factors we could not control for such as education and income that increase risk for the women giving birth in public hospitals.
The overall proportions of women classified as low risk who gave birth in private and public hospitals in NSW during the years 2000–2008 were similar for primiparous women but significantly different for multiparous women. A decade ago 48% of women in private and public hospitals were considered low risk. This compares with 43% in our study a decade later. In NSW, the caesarean section rate has increased from 19% in 1998 to 30.2% in 2009.16
The caesarean section rate is much higher for the private sector and has been accompanied by an even sharper rise over the past decade as seen in our research. MacDorman et al23
suggested that the rapid increase in the caesarean section rate from 1996 onward in the USA reflected two current trends: an increase in the primary caesarean section rate and a steep decline in vaginal birth after a primary caesarean section. A similar pattern is seen in Australia with increasing primary caesarean and repeat caesarean section rates.1
It is commonly asserted that the rise in the caesarean section rate is due to changing demographics, such as older women, obese women and more complex medical profiles, which are a reality today in many resource rich nations. However, in our study, which only included low-risk women, the rise in caesarean section was independent of these factors. Other studies and government reports have also shown the dramatic rise in caesarean section independent of these risk factors.1
Most concerning in this study was the fact that a low-risk primiparous woman has a 20% lower chance of having a normal birth (44%) if she gives birth in a private hospital under obstetric care in NSW than in a public hospital (64%). The implications for women and babies in terms of short-term and long-term morbidity3
are not insignificant. The cost of high intervention rates in childbirth is also significant to society. Tracy and Tracy8
studied the incremental cost increase to the public purse as interventions were introduced in the labour and birth process. They found that the relative cost of birth increased by up to 50% for low-risk primiparous women and up to 36% for low-risk multiparous women as labour interventions accumulated. An epidural was associated with a sharp increase in cost of up to 32% for some primiparous low-risk women, and up to 36% for some multiparous low-risk women. Private obstetric care increased the overall relative cost by 9% for primiparous low-risk women and 4% for multiparous low-risk women.8
The levelling-out of the caesarean section rate from 2006 onwards may reflect the changes in government policy, research and international trends.5
However, over the past decade while obstetric interventions have steadily increased among low-risk women receiving public hospital care by more than 5%, they have increased by over 10% among women receiving private obstetric care in private hospitals. This disparity between the two services in health (private and public) is concerning, especially when much of the care in the private sector is funded from the public purse and more importantly the taxpayer. While women choosing private healthcare are also taxpayers and hence entitled to subsidisation this subsidy needs to be associated with a requirement for accountability to the funder.