It is okay to have the occasional alcoholic drink during pregnancy, that's the conclusion of a new Australian research.

The "soon-to-be" controversial study says a glass or two of wine is not harmful for expectant mothers and their unborn children.

The findings are based on a study of more than 4700 pregnant women.

The research found that low levels of alcohol consumption during pregnancy - less than seven standard drinks a week and no more than two drinks at a time - were not associated with preterm birth or reduced fetal growth, reports the Herald Sun.

The study has been published in the British Journal of Obstetrics and Gynaecology this week.

Researchers from the Centre for Child Health Research at the University of WA (Western Australia) say moderate and high levels of drinking in early pregnancy are linked with an increased risk of preterm birth, even when women stop drinking before the second trimester.

They say the findings show the pattern and timing of drinking are important when estimating risks and suggest pregnant women be screened for binge drinking.