Durham University proves babies yawn in the womb
Hanging around in limbo in the womb waiting to grow may well be dull, so it is no wonder that foetuses yawn.
Scientists have shown for the first time that unborn babies yawn repeatedly in the womb.
But they do not believe it is because they are sleepy or bored. The most likely explanation is that foetal yawning is an essential process linked to brain development.
While it is well known that foetuses open and close their mouths, experts had disagreed over whether or not they were actually yawning.
But a new study carried out at Durham University, using high resolution ultrasound footage, has confirmed that babies really do yawn, and do it often.
Researchers used a standard definition of yawning to distinguish it from a foetus just opening its mouth.
A proper yawn involves a slow opening of the mouth to its full stretch, followed by more rapid closure.
'Maturing of brain'
Dr Nadja Reissland, who led the study of seven male and eight female foetuses from six to nine months, said: "The results of this study demonstrate that yawning can be observed in healthy foetuses...
"Unlike us, foetuses do not yawn because they are sleepy. Instead, the frequency of yawning in the womb may be linked to the maturing of the brain early in gestation."
Foetal yawns occurred more frequently than simple mouth openings early in pregnancy, but declined after 28 weeks.
In total, 56 yawns and 27 non-yawn mouth openings were observed from 58 scans. The findings are reported in the online journal Public Library of Science ONE.
Both humans and animals yawn, but why this behaviour has evolved is still an unsolved mystery, researchers said.
Theories suggest it may be linked to neurological function, regulating temperature or stress.