Thousands of Ontario women have caesarean births that could and should be avoided, says a new report commissioned by Queen's Park.

One in every five births in Ontario concludes with abdominal surgery despite mounting evidence that caesareans do not necessarily result in improved health for mothers or newborns, the report says.

The authors do say that about 40 per cent of the 28,235 caesareans performed in Ontario in 1988-89 - more than 11,000 - were done because the mother had had a previous caesarean.