Many Australian women who smoke don't quit during pregnancy, a study shows, and when they cut back it's only by a couple of cigarettes a day.
Queensland researchers studied the smoking prevalence among a group of more than 260 pregnant women at an antenatal clinic.
They found 37 per cent of the women were smokers before they fell pregnant, and this declined to about 25 per cent once they became aware of their condition.
Dietician and health psychology researcher Shelley Wilkinson, from the University of Queensland's School of Psychology, said the small reduction in smoking rates was consistent with the national trend.
"The disappointing thing is there still are 25 per cent who are still smoking," Ms Wilkinson said.
The disappointing thing is there still are 25 per cent who are still smoking.
Those who continued to smoke, Ms Wilkinson said, reduced their intake from an average of 16 cigarettes a day to 13.
Smoking during pregnancy increases the risk of miscarriage, and a host of health problems for the baby linked to an increased risk of premature birth and low birth weight.
Ms Wilkinson said the research showed the importance of improving services to help these women quit smoking.
"This is a time when the majority of women are in touch with a health service, and are motivated to make changes," Ms Wilkinson said.
"These women know that they need to give up but they need more help, so this is a time when we should be providing more services."
The study also found that more than 40 per cent of women in the study were overweight or obese, they consumed half the recommended serving of fruit and a third of the recommended serving of vegetables.
The research is published in the June issue of the Australian and New Zealand Journal of Public Health.