E-cigarettes are as safe to use as nicotine patches for pregnant smokers trying to quit, and may be a more effective tool, researchers have revealed.

Smoking in pregnancy can increase the risk of outcomes including premature birth, miscarriage and the baby having a low birth weight. But stubbing out the habit can be a struggle.

“Many pregnant smokers find it difficult to quit with current stop smoking medications including nicotine patches and continue to smoke throughout pregnancy,” said Dr Francesca Pesola, an author of the new study who is based at Queen Mary University in London.

While e-cigarettes have been found to be more effective than nicotine patches in helping people quit, Pesola noted there has been little research into their effectiveness or safety among pregnant women, despite an increase in use by expectant mothers.

Writing in the journal Nature Medicine, Pesola and colleagues describe how they randomly assigned 569 pregnant smokers to use e-cigarettes and 571 to use nicotine patches – a form of nicotine replacement therapy that can already be prescribed by during pregnancy. The participants were, on average, 15.7 weeks pregnant and smoked 10 cigarettes a day.

Only 40% of those given e-cigarettes and 23% of those given patches used their allocated product for at least four weeks. However, both uptake and duration of use during the study was higher among those given e-cigarettes.

After excluding participants who self-reported not smoking but who used nicotine products other than those allocated to them – for example those given patches group who used e-cigarettes – the team found those given e-cigarettes appeared to do better at quitting smoking.

Four weeks into their attempt to quit 15.4% of those given e-cigarettes self-reported they were not smoking, compared with 8.6% of those given patches, while 19.8% of the e-cigarette group self-reported abstinence at the end of pregnancy compared with 9.7% in the group given patches.

Only a small number of participants provided saliva samples to confirm smoking abstinence at the end of pregnancy, but once those who used non-allocated products were excluded, the team found higher rates of abstinence among the e-cigarette group.

In addition the team found the rates of adverse events were similar between those given cigarettes and those given patches. What’s more, while the average birth weight of the babies was similar, low birth weights were more common in the patch group.

However the study has limitations, including low adherence and that the e-cigarettes used in the study differ from modern pod devices.

The authors add that given questions remain about the potential risks of nicotine in pregnancy, it is preferable for pregnant women to quit smoking without using nicotine containing products.

“We would only recommend the use of nicotine to smokers wanting to quit their regular cigarettes,” said Pesola.

But, she added: “Using an e-cigarette poses no greater risk to the mother or baby than nicotine patches, which are both better options than continuing to smoke throughout pregnancy.”