November 22, 2012
Ultrasound Shows That Even Unborn Babies Yawn
Connie K. Ho for redOrbit.com — Your Universe Online
Bust a yawn in the room and others may follow suit. While yawning may be contagious with children and adults alike, the role of yawning is less clear in unborn babies.
The study on yawing as a developmental process was recently published in the international academic journal, PLoS ONE. While past studies by scientists have argued that fetuses yawn, other studies have proposed that unborn babies are only opening their mouths slightly, and not showing a true yawn. The scientists believe that the varied findings were the result of “a lack of precise definition of yawns” that differentiated them from mouth openings.
In the current study, the scientists completed 4D scans of 15 healthy unborn babies and the images show a clear difference between “yawning” and “non-yawn mouth opening.”
"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,” explained the study´s lead research Dr. Nadja Reissland of the Department of Psychology at Durham University in a prepared statement.
Based on the findings, the team of investigators believed that over half of the mouth openings found in the study could be considered “yawns.” Yawn studies were conducted with eight female and seven male fetuses during 24 to 36 weeks of gestation. While there was no major difference between yawning in males and females, yawning overall reduced following 28 weeks of gestation.
“The results of this study demonstrate that yawning can be observed in healthy fetuses and replicates previous studies with 2-D images. In contrast to previous research we could also show that although healthy fetuses vary in the frequency of yawns observed overall, the repeated measures design allowing an observation of the same fetuses at 24 to 36 weeks gestation in 4 weekly intervals showed that in healthy fetuses the frequency of yawning declines over time,” wrote the authors in the paper.
Scientists are still unsure as to the role of yawning, but believe that it may be related to fetal development.
"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," continued Reissland in the statement. "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.”
More research in the future is needed to identify how yawning could impact development in areas like the central nervous system.
“In order to exclude the potential function of cortisol in yawning, in future research it would be important to measure maternal cortisol levels at the time of observing fetal yawns,” concluded the authors..