How babies learn to make faces
Unborn babies practise facial expressions of pain in the womb, scientists have said.
Foetuses have been pictured, using 4D scanning technology, showing what appears to be pain.
The researchers, from Durham and Lancaster universities in England, suggest the ability to grimace is a developmental process that could help doctors assess the health of a foetus.
Published in the journal 'Plos One', the study found that when the mother was 24 weeks pregnant, unborn babies were able to make simple expressions.
By 36 weeks they were able to create "complex multi-dimensional expressions" such as pain.
Researchers, who examined video footage of 4D scans of 15 healthy babies, said the process was "adaptive" and helped the unborn child to prepare for life after birth.
Researchers hope further investigation will examine whether the development of facial expressions in the womb is delayed if the mother smokes or drinks during pregnancy.
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.
"This is so that they can communicate any distress or pain they might feel to their carers.
"This suggests that we can determine the normal development of facial movements and potentially identify abnormal development too."