Infant death rates and the rate of women smoking during pregnancy has declined since 2009, but this trend is not seen in all areas of Australia.

A new report shows babies born to mothers living in regional towns are 1.4 times more likely to die than those babies born to city-dwelling mums.

Women living in the Western NSW suburbs of Bathurst, Dubbo, Broken Hill and Orange are the most likely to smoke during pregnancy.

The Australian Institute of Health and Welfare report, released on Thursday, measured child and maternal health using four indicators: infant and young child deaths, birth weight, smoking during pregnancy, and antenatal care attendance in the first trimester of pregnancy.

Overall, the data shows infant death rates and the rate of women smoking during pregnancy has declined since 2009.

Despite the generally positive results nationally, these positive trends were not seen equally across Australia's 31 Primary Health Network (PHN) areas.

Nationally, mothers smoking during pregnancy had fallen from about one in seven mothers in 2009 to one in 10 in 2015.

But in some areas the rate was nearly 18 times as high as in others, said AIHW spokesperson Anna O'Mahony.

"The other indicators also varied, but to a lesser extent, with rates up to three times as high in some PHN areas," said Ms O'Mahony.

Northern Sydney PHN area - which takes in the the suburbs of Manly, Hornsby and Avalon - recorded the lowest rates for three of the four health indicators.

In contrast, Northern Territory PHN area (which covers the whole of the Northern Territory) had the highest rates low birth weight babies and infant and child deaths.

The Western NSW network (Bathurst, Dubbo, Broken Hill and Orange) had the highest rate of mothers smoking during pregnancy, with almost one in four mothers smoking at any time during pregnancy.

In general across all indicators, Aboriginal and Torres Strait Islander mothers and babies and those outside metropolitan areas recorded poorer results.

"For example, metropolitan areas had a rate of almost four infant and young child deaths per 1000 births. The rate was around 1.4 times higher in regional areas with about 5 deaths per 1000 births," Ms O'Mahony said.

Almost half (46.5 per cent) of Aboriginal and Torres Strait Islander mothers had smoked at some point during their pregnancy.