The authors of a new study published in the Medical Journal of Australia are calling for all couples considering pregnancy or in the early stages of pregnancy to be offered cystic fibrosis carrier testing.

The research is based on a prenatal testing clinic at Newcastle in New South Wales, where couples were offered the test by extracting DNA mouthwash samples.

Of the 1,000 individuals that took the test, the four couples deemed to be high risk changed their reproductive decisions to avoid having a child with cystic fibrosis.

Author Louise Christie says couples should be offered the option of having the test.

"I think that it's important for couples to have the information, for them to make the choices first off if they want to have the screening, because some couples do not want to know that information before they have a child," she said.

"Couples do face quite a lot of decisions in early pregnancy or before they have a baby about what tests are out there and what tests they find acceptable."