To the Editor: The current rate of caesarean sections in Australia (29% of all live births) is higher than the rate in other similarly affluent countries.1 In addition, the rate is continuing to increase; for example, it was less than 20% in 1993.1

Some commentators have suggested that this increase is partly a result of caesarean sections undertaken for non-medical reasons, such as patient demand.2,3 We examined trends in the rates of caesarean section for low-risk women using population-based perinatal data for Queensland over 15 years between 1990 and 2004. Our aim was to assess whether caesarean sections were becoming more common among women with no obvious medical indication for the procedure.

The increase in caesarean sections among low-risk women was most dramatic in the private health care sector, where the percentage increased from 10% to 19% (Box). This represents an average annual increase of 4.6% (95% CI, 4.3%–5.0%). In the public health care sector, the increase was less — from 6% to 8% — an average annual increase of 2.4% (95% CI, 2.0%–2.7%). The increase in the private sector in Queensland was similar to the increase reported in the United States.4

The appropriate use of caesarean section, as for any medical intervention, should be based on evidence about the benefits and harm, with doctors, women and their families choosing a method of delivery after considering balanced information on potential outcomes of each method. There is continuing debate about the feasibility of randomised trials to clarify the benefits and harm of caesarean deliveries among low-risk women.2 Opposition to such trials is based mainly on ethical concerns about inflicting a surgical procedure on healthy women based only on randomisation.

Non-randomised studies have compared outcomes of caesarean section versus vaginal delivery. However, their results are inconclusive because of the difficulty of distinguishing the effects of factors that influence the selection of delivery method from the effects of the delivery method itself (confounding by indication).3,5

In the absence of randomised trials, non-randomised studies that remove this potential bias by restricting the sample to women who remain at low risk throughout the pregnancy and delivery, according to clearly defined criteria, may provide useful information. They would need to assess both short-term and long-term outcomes. Until such better evidence is available, it is impossible to judge whether or not the current increase in caesarean section rates among low-risk women is desirable.

Caesarean section rates among low-risk* women in Queensland, 1990–2004

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* Low-risk births were defined as singleton, full-term (37–40 weeks’ gestation), vertex delivery with no reported medical risk factors or complications of labour or delivery, based on a list compiled by Declercq and colleagues.4 Women who had a previous caesarean delivery were excluded from the low-risk group.