Mother's yawn can make fetus yawn, study finds

A yawn from a pregnant mother can trigger a yawn in her fetus, according to a new study by Italian researchers. The study observed that when expectant mothers yawned, their fetuses in the womb also yawned shortly after, a pattern that occurred so consistently it suggested it was not mere coincidence.

During the experiment, 36 pregnant women between 28 and 32 weeks of gestation were shown videos of people yawning. Their facial expressions were recorded, while fetal movements were monitored via ultrasound. Researchers analyzed the footage frame by frame, distinguishing genuine yawns from other mouth movements. They found that fetuses yawned more often than expected by chance following their mothers' yawns.

Using a machine learning model, scientists compared the movement patterns of maternal and fetal yawns, noting similarities in how the mouth opened and closed. Previously, fetal yawning was largely considered an automatic movement generated by the fetus's own nervous system. However, these results indicate that bodily changes associated with the mother's yawn might also influence when the fetus yawns.

While the exact mechanism behind this connection remains unclear, researchers suggest that this synchronization between mother and fetus could represent an early foundation for social interaction development. The study was published in the journal Current Biology.