These images of 4-D scans of unborn babies have been released in an attempt to prevent women from smoking while pregnant.

The images depict a baby whose mother is smoking while the second set shows a non-smoking mother. The first set of images clearly show the baby writhing in the womb while the second set sees the baby quite peaceful.

According to the Daily Mail, Dr Nadja Reissland, of Durham University, used 4-D ultrasound scan images to record thousands of tiny movements in the womb.

She said: "A larger study is needed to confirm these results and to investigate specific effects, including the interaction of maternal stress and smoking."