The research project looked at all births in Western Australia between 1984 and 2003 (more than 430,000 births) and analysed the mode of delivery. It excluded multiple and breech births.
Report author, Colleen O'Leary, from Perth's Telethon Institute for Child Health Research, said that even after adjusting for pregnancy and delivery complications and sociodemographic factors, the increases were significant. Women in 1999-03 were twice as likely to have a caesarean section, than women in 1984-88.
"The figures show that what we call elective or planned caesareans have risen from 6 per cent to 13 per cent over the 20 year period and during the same time, there has been a 70 per cent increase in the number of emergency caesareans," Ms O'Leary said.
"From the analysis it is clear that both maternal age and affluence are factors in the increasing rates of caesareans.
"When we included private medical insurance into the analysis, we found that women who had medical insurance were more than three times as likely to have an elective caesarean section, and 1.34 times more likely to have an emergency c-section than those who were uninsured, even though pregnancy complications and obstetric problems which may need a caesarean section are higher in uninsured women.
"The increase in caesarean rates also has a significant impact on health costs in both the public and private sectors."
Report co-author, obstetrician Craig Pennell from the School of Women's and Infants' Health at the University of Western Australia, said the changes over the 20 year period in both elective and emergency caesarean suggest that th