NRL News

Ultrasounds demonstrate Unborn Babies do yawn

by | Nov 26, 2012

By Dave Andrusko

I thought we’d start the week after Thanksgiving off on a delightful note. Writing on the online international journal PLOS ONE, researchers from the University of Durham have conclusively demonstrated that unborn babies do yawn, just another example of their behavioral repertoire.

It’s already been proven that unborn babies can stretch, kick and leap even hiccup in the womb.

But how did Nadja Reissland, DPhil, from the Department of Psychology in the University of Durham in the United Kingdom, and her colleagues demonstrate that babies at 24, 28, 32 and 36 weeks of pregnancy actually yawned, not merely opened their mouths (as skeptics have insisted)?


They used 4 Dimensional ultrasound technology to scan 15 healthy babies while still in their mother’s womb, at four week intervals. “If the babies spent more than 50 percent of the time their mouths were open to open it to the widest point, the researchers classified that as a yawn,” explained Dr. Robert Carlson. “They also looked at whether the number of times the babies yawned changed with the weeks. They found that the babies yawned less and less after the 28th week of pregnancy.”

Dr. Reissland said the function and importance of yawning in fetuses is still unknown, but the findings suggest it may be linked to fetal development.

“Fetus yawning is not contagious, nor do they yawn because they are sleep,” Reissland said. “Instead, frequency of yawning in the womb might be related to activity-dependent brain maturation early in gestation.”

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Categories: Fetal Development