Fetuses Yawn in the Womb, Say Researchers

First Posted: Nov 22, 2012 04:44 AM EST

With the help of 4D scans researchers at the Durham and Lancaster Universities revealed that fetuses yawn.

The intelligent life in the womb cannot only produce hiccups but also react to loud sounds, experience rapid eye movement and they can even distinguish between voices. But there was a lot of confusion about whether the fetuses yawn or simply open their mouths.

This study shows that yawning is a developmental process which could potentially give doctors another index of fetal health.

This study distinguishes yawning from simple mouth opening. This was judged based on the duration of mouth opening. With the help of 4D video footage they closely examined all events where a mouth stretch occurred in the fetus.

With this criterion the researchers discovered that over half of the mouth openings observed in the study were seen as yawns.

In order to come out with a clear understanding of the difference between a simple mouth opening and a yawn, the researchers carried out a study on eight female and seven male fetuses from 24 to 36 weeks gestation. 

They noticed that yawning declined from 28 weeks and there was no striking difference in the yawn frequency of the boys and girls.

Though not much is known about the function and importance of yawning, the study highlights that yawning could be linked to fetal development, and as such could provide a further medical indication of the health of the unborn baby.

Lead researcher, Dr Nadja Reissland, of Durham University's Department of Psychology, said: "The results of this study demonstrate that yawning can be observed in healthy fetuses and extends previous work on fetal yawning. Our longitudinal study shows that yawning declines with increasing fetal age.

"Unlike us, fetuses do not yawn contagiously, nor do they 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.

"Given that the frequency of yawning in our sample of healthy fetuses declined from 28 weeks to 36 weeks gestation, it seems to suggest that yawning and simple mouth opening have this maturational function early in gestation."

They predict that yawning could be associated with central nervous system maturation but further research involving mother and fetus would be required to examine this theory.

Here is a video of a fetus yawning in the womb:

The study was published Nov 21 in the journal PLOS ONE.

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