The introduction of a test to help doctors identify smoking mums-to-be could help start discussions about the dangers of smoking in pregnancy.

The introduction of a breath test to identify smoking pregnant women could lead to healthier children, experts say.

Pregnant women could be breath tested to see if they smoke so health professionals can help them quit, a leading Australian anti-tobacco crusader says.

Fiona Sharkie, director of Quit Victoria, said while many women quit smoking when they discover they’re pregnant, others choose not to discuss smoking with midwives and doctors because they felt guilty about continuing.

New data shows that 14.6 per cent of expecting women said they'd smoked in the first 20 weeks of pregnancy 

For this reason, she said Australian health authorities could follow the UK’s lead and use breath tests so all women are tested and prompted to discuss the issue in pregnancy.

''There are other ways of bringing it up and supporting people to quit,'' she said.

New data on smoking rates for pregnant women in Victorian public hospitals shows that 14.6 per cent said they had smoked in the first 20 weeks of pregnancy. This dropped to 5.6 per cent after 20 weeks.

About 4 per cent of women attending private hospitals also smoked in the first five months, reducing to 2 per cent after 20 weeks, state government figures for 2009-10 reveal.

The report didn’t define how much the women smoked, so it could include some who smoked until they realised they were pregnant.

Smoking during pregnancy doubles the risk of stillbirth to about 2 per cent, and increases the risk of premature labour, cleft lips and cleft palates. Women who smoke are also more likely to give birth to small babies, who are more vulnerable to breathing problems and infections.

The report said smoking was most common among women in country areas.

Associate Professor Glyn Teale, an obstetrician and author of the government report, said although a lot of women were smoking in the first five months of pregnancy, he was pleased to see a significant reduction after 20 weeks, when most women would have had contact with midwives and doctors.

''Nearly two-thirds stop smoking during pregnancy, which is encouraging, but overall, too many women are smoking in early pregnancy,'' he said.

Professor Teale said he hoped the data would prompt services to assess their efforts in helping pregnant women quit. He said it was important for health professionals to repeatedly ask women about smoking while talking about the risks.