A group of public health physicians and researchers say nicotine replacement therapy should be prescribed to pregnant women who can't quit smoking.

Doctors are being encouraged to prescribe nicotine replacement therapy to pregnant women who find it too hard to quit smoking on their own in order to ensure the best health outcomes for the baby.

A research review published in the Medical Journal of Australia has found NRT is safer than smoking.

The authors, led by public health physician Dr Yael Bar-Zeev at the University of Newcastle, say doctors can be confident about prescribing it for their pregnant patients.

It's a call supported by Cancer Council Australia.

"We know that smoking has a significantly detrimental impact on the fetus, it leads to things like low birth weight, prematurity and a doubling of the risk of stillbirth," said Cancer Council CEO Professor Sanchia Aranda.

"What this study shows is that nicotine replacement therapy is as safe as we can make it, there's no evidence of adverse effects on the fetus and so the health risks of smoking are considerable and if this helps women give up then that's a good thing," said Professor Aranda.

Despite guidelines recommending its use for pregnant women unable to quit smoking unassisted, many clinicians are still reluctant to prescribe it due to "safety concerns", say Dr Bar-Zeeve and colleagues.

"A recent survey of Australian general practitioners and obstetricians, 25 per cent of participants stated that they never prescribe NRT during pregnancy," they wrote.

In animal studies, nicotine has been shown to cause damage to the lungs and central nervous systems of the fetus. However, human studies "did not find any harmful effects on fetal and pregnancy outcomes."

"Nicotine may not be completely safe for the pregnant mother and fetus but it is always safer than smoking," the researchers concluded.

Quit Victoria director Dr Sarah White says as a first step pregnant women should try behavioural interventions to help them quit smoking.

"But if that's not working for them, pregnant women should not be concerned about using nicotine replacement products as well," she said.

"While nicotine replacement products do contain nicotine, unlike cigarettes they don't contain thousands of cancer-causing toxic chemicals like tar and carbon monoxide so they're nowhere near as harmful as smoking for the woman or unborn child."