Unborn babies practise facial expressions showing pain while they are in the womb, a study has claimed.
Researchers from Durham and Lancaster Universities say a foetus' ability to show pain through facial expressions is a developmental process which helps the unborn baby prepare for life after birth.
The research was carried out by creating scans of 15 healthy foetuses, and could give doctors another index of the health of an unborn baby.
The study showed a foetus is capable of making simple one-dimensional expressions at 24 weeks, such as the ability to move the lips to form a smile.
By the time a mother is 36 weeks into her pregnancy, a foetus can perform complex multi-dimensional expressions which can be recognised as showing pain.
Lead researcher Dr Nadja Reissland, of Durham University's Department of Psychology, said: "It is vital for infants to be able to show pain as soon as they are born so that they can communicate any distress or pain they might feel to their carers.
"Our results show that healthy foetuses 'learn' to combine the necessary facial movements before they are born.
"This suggests that we can determine the normal development of facial movements and potentially identify abnormal development too. This could then provide a further medical indication of the health of the unborn baby."
The study is due to be published in the academic journal PLOS ONE.