These startling images show the real effects of smoking while pregnant.

These images should be enough to encourage any expectant mum to put the cigarettes down.

Doctors have long warned that smoking while pregnant is bad for your baby’s development — but until now, we’ve never seen images showing just what that harm looks like on unborn babies.

And experts are hoping the scans will encourage mums struggling to put the cigarettes down and quit smoking.

In the image below, the baby featured at the top is the foetus of a smoking mother, while the baby on the bottom is that of a non-smoking mum.

According to Dr Nadja Reissland, who conducted the research at Durham University, babies should touch their face and mouth less the further along they develop.

These images show that cigarettes can delay the development of the baby’s central nervous system.

Read more: WATCH: Here’s how far behind Australia the rest of the world is on tobacco.

Dr Reissland monitored 20 pregnant women attending James Cook University Hospital in Middlesbrough using 4-D ultrasound scan images to record movements of babies in the womb at 24, 28, 32 and 36 weeks.

Four of the mothers smoked an average of 14 cigarettes a day.

The study concluded that foetuses of smoking mothers showed significantly higher rates of mouth movement and self-touching than those of non-smoking mums.

Read more: Mothers and midwives weigh in: Your biggest fears about childbirth eased.

Doctors warn that smoking while pregnant is the biggest contributing factor to development of complications during pregnancy. It can lead to asthma, middle ear disease, poor lung development, respiratory problems, behavioural issues and even cot death.

Listen to Dr Reissland explain her findings below…