Government figures reveal 267,793 women gave birth to 272,419 babies between 2004 and 2005 - a 6 per cent jump from the previous year.
First-time mums are continuing to put off starting their families until they are on the brink of 30, with the average age being 29.8 years, compared with 28.6 in 1996.
'For first-time mothers, the mean age was 28 years in 2005 - about a year and a half older than first-time mums in 1996,' said Dr Elizabeth Sullivan, from the Australian Institute of Health and Welfare's national perinatal statistics unit.
A consequence perhaps is the number of pre-term babies has increased by just under 10 per cent in the past decade reports the Daily Telegraph.
'It is a significant increase - almost 10 per cent increase in the rate,' Dr Sullivan said Thursday.
'Some of the reasons are issues around increased fertility treatment - there are higher rates of pre-term births due to higher rates of double embryo transfer.
'Also, women with complicating medical conditions are more likely to get pregnant and the increase in maternal age will (mean) higher numbers of pre-term births.'
The report showed obstetricians' preference for caesarean sections has not abated, with 30.3 per cent of women in 2005 giving birth by C-section, compared with 19.5 per cent in 1996.
Women giving birth in private hospitals reported higher rates of caesarean sections and, of those women who had previously had a caesarean section, 83.2 per cent had another surgical birth.
The report showed that a significant number of pregnant women smoke, with 17.4 per cent of those surveyed reporting lighting up while pregnant.
For the first time, the Australia's Mothers and Babies report tied maternal socio-economic status to health outcomes such as birthweight and found that being well-off was an advantage in terms of birth outcomes.
'Poorer outcomes such as pre-term birth and low birth weight were more common in the less advantaged groups,' Dr Sullivan said.
Likelihood of interventions such as induction, instrumental delivery or caesarean section increased with socio-economic advantage, and mothers in the most advantaged groups were less likely to smoke during pregnancy.
The caesarean pattern also can be seen in New South Wales, with the latest data showing mothers going under the knife increased from 23.6 per cent in 2001 to 28.1 per cent in 2005.
The State Government is investigating delivery rates and why women were increasingly opting for a caesarean.