(TELEGRAPH) — Spending six months in the womb is enough to make a foetus yawn, as this image from an ultrasound scan shows.
But rather than being a sign of tiredness or boredom, scientists believe that yawning could help trigger the development of the foetus's brain.
Making the complex muscle movement could send nerve impulses into the brain, helping to program it for normal functioning, researchers said.
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Images of foetuses apparently yawning have provoked debate among some scientists, with some claiming the developing babies were simply opening their mouths.