Unborn babies not only hiccup, swallow and stretch in the womb, they also yawn, a new study says. The 4D scans of 15 healthy foetuses by Durham and Lancaster Universities, also suggest that foetal yawning could potentially give doctors another index of a foetus' health.
While some researchers suggest that foetuses yawn, others disagree and claim that it is simple mouth opening. However, the new research clearly distinguishes 'yawning' from 'non-yawn mouth opening' based on the duration of mouth opening. The researchers did this by using the 4D video footage to closely examine all events where a mouth stretch occurred in the foetus.
The research team found that over half of the mouth openings in the study were yawns. The study was made on eight female and seven male foetuses from 24 to 36 weeks gestation. The researchers found that yawning declined from 28 weeks and that there was no significant difference between boys and girls in yawning frequency.
Although the importance of yawning is unknown, the study suggests that yawning could be linked to foetal development. Foetuses do not yawn contagiously, nor do they yawn when sleepy. Instead, the frequency of yawning in the womb may be linked to the maturing of the brain early in gestation.