Yawning is one of those everyday human behaviours that almost everyone experiences and almost nobody fully understands. It spreads easily from person to person, often without warning.
Seeing someone yawn, hearing about yawning or even reading the word can sometimes trigger the same reaction. Now, scientists say this strangely contagious behaviour may begin much earlier than previously believed, even before birth.
A new study suggests that fetuses may be able to "catch" yawns from their mothers while still in the womb, offering a fascinating glimpse into how human social and physiological behaviours may begin developing during pregnancy.
What the study discovered
The research, published in Current Biology, was carried out by scientists at the University of Parma.
Researchers recruited pregnant women with healthy and uncomplicated pregnancies and observed how both mothers and fetuses responded to different facial expressions shown in videos.
The women watched several clips, including:
- People yawning
- People opening and closing their mouths
- Still faces without movement
While the mothers watched the videos, cameras recorded their facial expressions and a 2D ultrasound monitored the fetuses' facial movements in real time.
The surprising response from fetuses
As expected, many of the mothers yawned while watching the yawning videos. Around 64 per cent yawned at least once during those clips, while very few reacted during the non-yawning videos.
What surprised researchers was what happened inside the womb.
According to the study, around 53 percent of fetuses also appeared to yawn when their mothers watched yawning videos. In many cases, the fetal yawns happened roughly 90 seconds after the mothers yawned.
Researchers also noticed an interesting pattern. Mothers who yawned more frequently tended to have fetuses that yawned more as well.
The study described this as a "robust positive association" between maternal and fetal yawning frequencies.
Why scientists find contagious yawning so fascinating
Contagious yawning has long intrigued scientists because it appears connected to social bonding, empathy and neurological development.
Humans are not the only species known to experience it. Some primates, dogs and other social animals also appear capable of contagious yawning.
However, researchers still do not fully understand why it happens.
The new findings suggest the behaviour may begin as a basic physiological response before evolving into a more socially driven action later in life.
What could be happening inside the womb?
The researchers say the fetal reactions are unlikely to be conscious imitation in the way older children or adults mimic one another.
Instead, they believe the response may be linked to internal bodily signals triggered by maternal behaviour.
The authors suggested the phenomenon may reflect "intrauterine physiological contagion", meaning changes in the mother's body could influence fetal behaviour through interconnected biological processes.
In simple terms, the fetus may be reacting to subtle physical changes happening in the mother after she yawns.
A new perspective on early human development
The study adds another layer to what scientists know about fetal development and early behavioural patterns before birth.
Researchers believe contagious yawning could represent a motor behaviour that develops very early and later becomes connected to social interaction after birth.
While many questions remain unanswered, the findings offer a rare look at how some of the body's most familiar behaviours may begin long before a baby enters the world.
And yes, after reading all this, there is a good chance you may have yawned too.