There has been an increase in the number of babies born in Australia for the first time in five years.

The latest figures from the Australian Institute of Health and Welfare (AIHW) show that over 307,000 mothers gave birth to more than 312,000 babies in Australia in 2012.

Those figures were up 3.4 per cent from 2011 and 21.5 per cent since 2003.

The overall birth rate was 65 per 1,000 women, which is the highest rate in the last decade and similar to the 2007 birth rate of 64.9 per 1,000 women.

AIHW spokeswoman Dr Georgina Chambers said the average age of mothers in Australia had also steadily increased, from 29.5 years in 2003 to 30.1 years in 2012.

Number of births in 2012 Location Mothers Births Australia 307,474 312,153 New South Wales 98,138 99,507 Victoria 77,170 78,393 Queensland 62,650 63,709 Western Australia 33,393 33,862 South Australia 20,338 20,666 Tasmania 5,863 5,940 Australian Capital Territory 5,939 6,046 Northern Territory 3,983 4,030 Source: Australian Institute of Health and Welfare

"About 42 per cent of women who gave birth in 2012 had their first baby, and the average age for first time mothers was 28.4 years," she said.

"Over the last decade the proportion of older women giving birth continued to rise, while the proportion of teenage births continued to fall.

"Mothers aged 35 years and older made up more than 22.4 per cent of all women giving birth in 2012 compared to 18.8 per cent in 2003.

"Conversely teenage births declined from 4.6 per cent in 2003 to 3.6 per cent in 2012."

Overall, 4 per cent of women who gave birth during 2012 identified as Aboriginal or Torres Strait Islander.

Indigenous mothers tended to be an average of five years younger than non-Indigenous mothers.

The AIHW figures show smoking during pregnancy was reported by more than 12 per cent of all mothers in 2012 and in almost 35 per cent of teenage mothers.

Almost half of Indigenous mothers reported smoking during pregnancy.

Overall, 6 per cent of babies were of low birthweight (less than 2,500 grams) and this doubled among mothers who smoked during pregnancy.

About a third of all babies born in 2012 were delivered by caesarean section.

"Caesarean sections rates ranged from 17.1 per cent for teenage mothers to 49.9 per cent for mothers aged 40 and over," Dr Chambers said.

An estimated 4 per cent of women who gave birth received assisted reproductive technology.

The perinatal death rate was 9.6 per 1,000 births, with 7.2 stillbirths per 1,000 births and 2.4 neonatal deaths (death of an infant within 28 days of birth) per 1,000 live births.

Tasmania has 'smallest birth rate increase in the country'

The report shows Tasmania is bucking the trend when it comes to birth rates.

In Tasmania, there was a 4 per cent rise in the number of births in the same period, the smallest increase of any state or territory.

The report's socio-economic survey of births also revealed more than half the Tasmanian women who gave birth in 2012 lived in the most disadvantaged areas of the state.

This was markedly higher than any other state.

Tasmania also had the highest rates of neonatal deaths, at 3.2 per 1,000 live births.

The leading cause in Australia for neonatal death was congenital abnormality.

The state also had the highest proportion of pre-term births in the country, at more than 10 per cent and the largest number of transfers to another hospital.

ACT, Victoria have highest average age for mothers

The ACT and Victoria have the highest average age for women giving birth.

In 2012 the average age of women giving birth in the ACT and Victoria was 30.7 years old, compared with the national average age of 30.1 years.

The lowest average age for mothers was in the Northern Territory at 28 years old.

Conversely the ACT had the lowest teen pregnancy rate at just 2.2 per cent, while the NT had the highest rate at 9.7 per cent.

The smoking rate for women in the Territory was also the lowest in the country, with less than 8 per cent of expectant mothers lighting up, compared with a national rate of more than 12 per cent.

Women giving birth in Canberra are also less likely to use pain relief during labour compared to more than 80 per cent of mothers in Western Australia.

The rate of caesareans was significantly higher in Canberra's private hospitals than in the public ones.