When Fetuses Yawn In The Womb | WAMU 88.5 - American University Radio

NPR : News

Filed Under:

When Fetuses Yawn In The Womb

Why people yawn is a mystery. But yawning starts in the womb.

Past studies have used ultrasound images to show fetuses yawning, but some scientists have argued that real yawns were getting confused with fetuses simply opening their mouths.

So Nadja Reissland, a researcher at the University of Durham in the United Kingdom, used a more detailed ultrasound technique to get images of fetal faces that could distinguish a true yawn from just an open mouth.

"They seem to open their mouths widely much less often than they yawn," Reissland says.

What's more, she found that yawning was common at 24 weeks but then dropped to zero at 36 weeks, according to a report by Reissland and her colleagues in the journal PLOS ONE.

Reissland believes that fetal yawning may somehow help trigger brain maturation, by acting as a kind of self-stimulation for the developing fetus.

"It could be that yawning is something which you need in order to have a functioning brain, which is a hypothesis," she says, adding that she would like to compare yawning in healthy fetuses, like the ones she studied, with yawning in fetuses that have medical conditions.

Reissland says she suspects that yawning has a different function for adults than for fetuses. Most studies on yawning have focused on its contagious nature. But some research suggests that children are immune from "catching" another person's yawn until about five years of age.

And Reissland says one study showed that babies don't imitate their mother's yawns, even though babies do imitate mouth movements such as smiles and pursed lips. "How is it possible that these babies can imitate mouth movements, but they don't imitate the yawning?" Reissland wonders.

Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.

NPR

Leonard Nimoy's Mr. Spock Taught Us Acceptance Is Highly Logical

The Star Trek actor died Friday in Los Angeles, and NPR TV Critic Eric Deggans says Nimoy's signature role taught fans the power of accepting their differences rather than fighting them.
NPR

When Food Is Too Good To Waste, College Kids Pick Up The Scraps

Millions of tons of food are wasted on college campuses around the country, and students are noticing. Some of them are now rescuing food to make tasty meals for the needy and compost for gardens.
NPR

Jeb's Rowdy Supporters Help Him Escape The CPAC Lion's Den

The former Florida governor's supporters shouted down his hecklers at his much anticipated appearance at the Conservative Political Action Conference.
NPR

A Neuroscientist Weighs In: Why Do We Disagree On The Color Of The Dress?

Robert Siegel speaks with Dr. Bevil Conway, a neuroscientist at Wellesley College, about the dress that has the whole Internet asking: What color is it?

Leave a Comment

Help keep the conversation civil. Please refer to our Terms of Use and Code of Conduct before posting your comments.