Tens of thousands of Australian women with low risk of birth complications are undergoing unnecessary medical interventions in private hospitals in a trend that a leading midwifery expert has described as "horrifying".
In a landmark study of nearly 700,000 women in NSW hospitals, those giving birth privately were found to have a 20 per cent lower chance of having their first child through normal vaginal delivery.
"The fact that these procedures which were initially life saving are now so commonplace and do not appear to be associated with improved [baby] death rates demands close review," found the study, to be published today in the British Medical Journal's open journal.
"The findings … suggest a two-tier system exists in Australia without any obvious benefit for women and babies and a level of medical overservicing which is difficult to defend."
The leader of the study, Hannah Dahlen, said the women examined were aged 20 to 34, were not pre-term or overdue and carried babies of normal weight. The study was conducted between 2000 and 2008.
There is a strong incentive for surgeons to 'schedule in' women for induced births to make their workload and patient flow easier to manage
"We looked at the healthiest, wealthiest population possible, exploding some of the myths out there that women receiving these interventions are sicker," said Professor Dahlen, a professor of midwifery at the University of Western Sydney.
While 35 per cent gave birth with no intervention in public hospitals, this dropped to 15 per cent in private hospitals.
"These are horrifying figures," Dr Dahlen said. She rejected the idea that women in private hospitals might be more risk averse and therefore requesting the interventions.
"A recent Queensland study surveyed women to see if those in private hospitals were more likely to request a caesarean section but found there were no difference," she said.
"Women need to be informed that intervention in childbirth is no walk in the park, with caesarean sections, for example, potentially causing a scarred uterus, which can increase the risk of complications in future pregnancies."
Obstetricians highly trained in dealing with complications were overseeing the care of low-risk women, Dr Dahlen said, and had a tendency to see all births as risky until the baby was delivered.
"There is also strong incentive for surgeons to 'schedule in' women for induced births to make their workload and patient flow easier to manage," she added.
Dr Dahlen recommended that the intervention rates of obstetricians should be made public, for example through the government's MyHospitals website.
But a senior specialist and the president of the Royal Australian and New Zealand College of Obstetricians, Rupert Sherwood, said comparisons between public and private hospital births should be done in the context that they were different groups of women with varying needs.
"We've always known the intervention rates are different between public and private hospitals," Dr Sherwood said.
"We have no idea if the women in this study were choosing interventions like caesarean sections or not because the researcher did not ask women that.
"But we have good evidence that the women giving birth in private hospitals are more risk averse."
Obstetricians were trained to assess women's individual circumstances and recommended accordingly, according to Dr Sherwood.
"The continuity of care provided to women by their obstetrician leads to a better-informed patient," he said.