By Stephen Beech
Yawning in the womb may be the unborn baby showing distress, according to new research.
Fetuses can – and do – yawn in the womb, where all oxygen is provided by the placenta, scientists say.
Now, a new study suggests that more frequent yawns are associated with a lower weight at birth – potentially indicating mild fetal stress in the womb.
Study author Dr. Damiano Menin, of the University of Ferrara in Italy, said: “Yawning is a behaviour found across vertebrates – and no one quite knows why.
“In humans, fetuses yawn in the womb from about 11 weeks.
“Even though there is no air to breathe, they slowly open their mouths, make motions similar to inhalation and exhalation, and close their mouths again.”
To understand more, the research team used ultrasound to observe 32 healthy foetuses between 23 and 31 weeks. Each one was observed for 22.5 minutes.
The findings, published in the journal PLOS One, show that the foetuses yawned up to six times during the observation period, with an average of 3.63 yawns per hour.
The research team also found that the unborn babies that yawned more during the study period were more likely to have a low weight at birth, which is considered as an indicator of mild distress, although all the babies in the study were born healthy.
Dr. Menin said the researchers did not perform any manipulations to see if they could affect foetal yawning, and didn’t record measures such as fetal heart rate or maternal temperature, which might potentially be associated with yawning.
Based on their findings, he suggests that frequent fetal yawning might be a sign of mild distress in the healthy baby.
Dr. Menin added: “We found that yawning frequencies in the womb are negatively related to birth weight, potentially indicating a stress-related response in healthy foetuses.
“This suggests that even before birth, yawning may serve as an indicator of a foetus’s well-being.”
