A longitudinal study published by Curtin University researchers on Wednesday examined 23 years' worth of records and histories of 63,540 Australian women with more than one child who smoked during their first pregnancy.

Lead researcher Gavin Pereira, from Curtin's School of Population Health, said more than one third of women who smoked during pregnancy were able to stop for their next pregnancy.

"(This) could reduce the risk of early birth in subsequent pregnancy by as much as 26 per cent," Professor Pereira said.

"What is clear from the study, is that maintaining quit messages and support for women who smoked during pregnancy, even after birth can have a significantly positive outcome for both them and their subsequent babies."

The latest figures from the Australian Institute of Health and Welfare show that 75 per cent of smokers continued to smoke beyond 20 weeks gestation.

"The second trimester is vital to an unborn babies' growth and formation - organs continue to develop, and the liver, pancreas and kidneys all start to function," Prof Pereira said.

"Despite smoking during a first pregnancy, woman can turn this around for their next pregnancy to reduce complications to their unborn."

Australian Associated Press