Yawns Seem to Be Infectious to Fetuses, Too

Even in the womb, it seems, a yawn is hard to resist. In a small study of 38 women in their third trimester, Italian researchers found that when moms-to-be yawned while watching videos of people yawning, their fetuses often followed suit—typically about 90 seconds later, reports Smithsonian Magazine. Overall, 64% of the women yawned during the yawn clips, and about 53% of their fetuses yawned as well, compared to almost no response during non-yawning videos. The findings, published in Current Biology, suggest fetal yawns may not be a simple reflex but can be triggered by maternal cues.

"Mothers who yawned more also tended to have fetuses that yawned more, revealing a robust positive association between maternal and fetal yawning frequencies," notes the research team from the University of Parma, per Science Alert. Researchers aren't yet sure how it works: Fetuses might sense the mechanics of a yawn or respond to hormonal changes. Nor is it clear why prenatal yawning exists, though lead author Giulia D'Adamo says pregnancy is all about "groundwork" for life after birth.