Expectant Australian mothers are older on average and accessing more antenatal care compared to a decade ago, with birth rates falling to the lowest since records began.

In 2023, 79 per cent of women who gave birth accessed antenatal care in their first trimester of pregnancy, a report on mothers and babies by the Australian Institute of Health and Welfare (AIHW) found.

This is an increase from 61 per cent who accessed antenatal care in 2013.

The average age of women who gave birth increased from 28.9 years in 1998 to 31.3 years in 2023.

The birth rate was 52 babies per 1000 women, the lowest since the AIHW began keeping records in 1998.

It shows a generally decreasing trend since 2007, when the birth rate was 66 babies per 1000 women.

"Over time, the proportion of women giving birth aged 35 and over has increased from 23 per cent in 2010 to 28 per cent in 2023, while the proportion aged under 25 has decreased from 18 per cent to 11 per cent," AIHW spokesperson Louise Catanzariti said.