Foetuses in the womb appear to flinch while their mother is smoking, new British research using ultrasound shows.

The captured images show foetuses cringing and touching their faces as their mothers smoke, yet researchers said facial touching should tail off as babies develop in the womb.

Researchers hope to use the new findings to encourage women not to smoke while pregnant.

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The researchers, from Durham University, studied 20 mothers, four of whom smoked, towards the end of their pregnancies.

The four mothers who smoked had about 14 cigarettes a day.

The mothers were scanned four times each with high definition ultrasound between the 24th week and the 36th week.

“Rates of foetal mouth-movement and facial self-touch differ significantly between smokers and non-smokers,” the study’s abstract states.

“Foetuses of smoking mothers showed a significantly higher rate of mouth movements compared to foetuses of non-smoking mothers, after controlling for maternal stress and depression.

“As pregnancy progressed, these differences between the smoking and non-smoking groups widened.

“A larger study is needed to confirm these results and to investigate specific effects, including the interaction of maternal stress and smoking.”