Pregnant women are being warned about the potential dangers of using e-cigarettes.
A new study from the University of Technology in Australia has linked vaping to an increased risk of asthma in children.
Researchers are due to present the findings at the European Respiratory Society International Congress tomorrow.
The study saw a number of female mice subjected to either e-cigarette vapour - with or without nicotine - or to normal room air before, during and after pregnancy.
Human cells were also exposed to varying concentrations of e-cigarette liquid as part of the research in order to measure the impact on the cell's mitochondria (the molecules that power key cell processes).
Dr Pawan Sharma of the University of Technology in Australia explained: “Our study found that maternal vaping increased the risk and severity of allergic asthma in offspring."
The study also found that "vaping, even without nicotine present, has a demonstrated negative impact on cell function".
Dr Sharma added: “These findings highlight that e-cigarette use during pregnancy should not be considered safe."
The Irish Vape Vendors Association, however, is criticising the research.
Spokesperson Gillian Golden says vaping is a safer alternative to smoking.
Recent research found that vaping is 'far safer' than smoking - smokers who moved on to e-cigarettes experienced “substantially reduced” levels of carcinogens and toxins compared to those who continued smoking.
Gillian observed: "A lot of these media headlines can cause a sort of distress in a vaper - they may think that they're better off smoking because vaping is not better for them. That's not the case."
Additional reporting by Stephanie Grogan