Where a woman gives birth - in a public or private hospital - is a key determinant of whether she has a caesarean section or not, according to findings from three consecutives surveys of more than 14,000 women who had recently given birth in Queensland.
Dr Yvette Miller from QUT's IHBI (Institute of Health and Biomedical Innovation) conducted the Queensland Government-funded surveys of different cohorts of women in 2009, 2010 and again in 2012.
"Queensland's caesarean rate is the second highest in Australia, after WA, and is rising steadily - 25 per cent in 2001 to 33 per cent in 2011," Dr Miller said.
"In Queensland private hospitals almost 50 per cent of births are by caesarean but in the public hospitals it is fewer than 30 per cent.
"Obstetric doctors have said this difference is largely driven by the higher number of older women with more risk factors in the private system or more women who want a caesarean."
Dr Miller said the results from surveys had shown that was not the case.
"Differences in women's age, obstetric risk, medical complications or education are not driving the higher rates of caesareans in the private sector," Dr Miller said.
"Nor are women's preferences accounting for the higher rate as we found no difference between women in the private and public sectors in their pre-existing preferences for a vaginal or caesarean birth." Only 10 per cent of women in both the private and public sector reported a pre-existing preference for a caesarean birth.
The surveys asked women to provide information on where they had given birth, their type of delivery, risk factors, preferences and freedom to choose their mode of birth. They asked the same questions of a different group of women each year and were carried out by Dr Miller with the Queensland Centre of Mothers and Babies, in partnership with the Queensland Registry of Births, Deaths and Marriages.
"We invited our survey participants from an independent source - the Queensland Registry of Births, Deaths and Marriages to overcome any 'gratitude bias' whereby some women might have felt they couldn't criticize the institution in which they had had their baby," she said
"Women said they weren't provided with information about the options for their birth or the right to choose what they wanted. They said such things as:
'While I had the option of either a vaginal or caesarean birth, I felt strongly urged to have a caesarean. I didn't want to have a caesarean but I decided to, based on two obstetricians strongly advising me to do so.'
'I was strongly discouraged from having a caesarean in the public system and at this time I found this quite stressful as I didn't feel I had complete control of all my decisions.'
Dr Miller said that women birthing in public hospitals were largely cared for by midwives and in private hospitals by obstetricians.'
"These professional groups perceive risks differently for each birth option so they might emphasise the dangers of one and the benefits of the other when communicating with women," she said.
"Different financial rewards are associated with each type of birth in the different sectors. The higher costs of caesarean are borne by the patient in the private sector and benefit the provider.
"Whereas in the public hospitals, the higher costs of caesarean are borne by the system, so the financial incentives of limiting women's options to one or other are different in each sector.
"Our research clearly demonstrates that it is not age nor other risk factors that are responsible for the difference. As women's preferences in wanting a vaginal birth are also the same, theoretically the caesarean section rates should be the same in public and private hospitals."
Dr Miller's work was published in the journal Midwifery: Going public: Do risk and choice explain differences in caesarean birth rates between public and private places of birth in Australia? in 2012.
Media contact: Niki Widdowson, QUT media contact, 07 3138 2999 or email@example.com.