Fetuses Can ‘Catch’ Yawns From Their Mothers While Still in the Womb, New Research Suggests

Yawning is considered a social behavior. While fetuses were known to yawn, scientists weren’t sure if it was a self-contained reflex or if they could somehow detect cues from their moms

Sarah Kuta | Daily Correspondent

May 14, 2026 10:00 a.m.

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Yawning is a highly contagious behavior. Stand next to someone who sleepily opens their mouth to take a deep breath, and, within a matter of seconds, you’ll likely find yourself doing the same.

Now, new research suggests even fetuses are not immune to the catchy power of a yawn. Laboratory experiments involving pregnant women suggest they can spread yawns to their soon-to-be-born offspring, researchers report in a study published May 5 in the journal Current Biology.

Scientists have long known that fetuses yawn, even though they cannot yet use their lungs to breathe. But they’ve wondered whether prenatal yawning was simply a self-contained reflex, or if fetuses were somehow responding to cues from their mothers.

To find out, researchers recruited 38 women between the ages of 18 and 45 who were in their third trimester of pregnancy. The participants were each carrying just one fetus—no twins, triplets or multiples—and had healthy, uncomplicated pregnancies.

The scientists showed each woman a series of videos: some showing people yawning, some showing people opening and closing their mouths and some showing people’s still faces. Throughout the experiments, a camera recorded the mother’s face, while a 2D ultrasound machine monitored the fetus’s nose and lips in real time.

As expected, the yawning clips elicited a response in moms. About 64 percent of participants yawned at least once while viewing them, while barely anyone demonstrated the behavior with the other types of videos.

What’s more, around 53 percent of fetuses yawned when their mothers watched the yawning videos, the researchers found. Fetal responses typically took place roughly one and a half minutes after their moms yawned. Participants who yawned more also tended to have fetuses that yawned more.

Scientists don’t fully understand how or why fetuses seem to “catch” yawns from their mothers, but they have a few hypotheses. One possibility is that fetuses can feel the physical movement of their mother’s yawn, which triggers their own yawn. The behavior might also somehow be prompted by hormones.

Another open question is whether these prenatal yawns serve any specific purpose or provide any benefit to the fetus. “During pregnancy, everything is groundwork for what is going to happen next,” says lead author Giulia D’Adamo, a neuroscientist at the University of Parma in Italy, to Science News’ Erin Garcia de Jesús.

Future studies might explore the contagiousness of yawns at various stages of pregnancy to better understand when the behavior first emerges and whether it changes throughout fetal development.

Humans are not the only creatures that instinctively yawn when they see, hear or even think about others yawning. Other social creatures also mimic each other when they open their mouths wide, including chimpanzees, lions, dogs and parakeets. It’s not entirely clear why yawns seem to be contagious, but scientists suspect the behavior may have evolved to synchronize behavior or increase vigilance within a group.

“If yawning is an indicator that one individual is experiencing diminished arousal, then seeing another person yawn might, in turn, increase the observer’s vigilance to compensate for the low vigilance of the yawner,” Andrew Gallup, an evolutionary biologist now at Johns Hopkins University, told Science’s Tess Joosse in 2022. “The spreading throughout the group of contagious yawns might then increase the vigilance of the entire group.”

Yawns may have other benefits, too. They seem to help promote alertness, as well as cool down the brain when its temperature rises, per Science.

And new research, published last month in the journal Respiratory Physiology & Neurobiology, suggests yawning may also play a role in clearing waste from the brain. The small study, which involved 22 participants, indicates yawning might help facilitate the movement of fluid along the brain’s waste-clearance pathway, known as the glymphatic system.

“If you sleep well, the glymphatic system is doing its job,” says W. Christopher Winter, a neurologist and sleep specialist with Charlottesville Neurology and Sleep Medicine who was not involved with the new paper, to Korin Miller at Women’s Health. “If you are not sleeping enough—or well—then the yawn suddenly starts to feel like your brain saying, ‘If you are not going to sleep properly and engage this glymphatic system, then we are going to turn on the back-up pump or hydraulic system.’”

Sarah Kuta | Read More

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.