Just like a supermarket avocado, the squishiness of fertilized human eggs could hint at how healthy and viable their embryos are—which would be a huge benefit for the millions of in-vitro fertilization babies now being born worldwide.


Today, scientists at Stanford University announced that the squishiness of an hour-old fertilized egg could help predict whether the egg would lead to a successful, healthy IVF pregnancy and birth. The technique was published in the journal Nature Communications.

IVF works by scientists injecting sperm into an egg. Then, they wait and see how many blastocyst cells start dividing. This is how embryo viability has been measured in the past—the more cells that reproduce, the better. But now, giving that microscopic, proto-human a good squeeze could prove a more accurate indicator.


“A lot of twins are born because we don’t know which embryos are viable or not, so we transfer several at one time,” said bioengineer Livia Yanez, who co-led the study. “This can increase the risk of neonatal mortality and cause complications for babies and the mothers.”

So the team decided to apply pressure to hour-old fertilized mouse eggs using a tiny pipette. The squishier eggs that “pushed back” ended up being less deformed than the others at the blastocyst stage. Using this data, the team ginned up a computation model that can predict with 90 percent accuracy whether a blastocyst will be symmetrical, form a healthy embryo, and lead to a complication-free birth.

Sure enough, when the embryos formed from squishier eggs were transferred to female mice, the animals were 50 percent more likely to deliver a normal live birth than if conventional IVF techniques were used. Finally, the Stanford team repeated the experiment with human eggs—and found that the likelihood of predicting healthy blastocysts using the squishiness method skyrocketed 90 percent.


What’s still unclear is why the squishiness of eggs is such a solid predictor. But what we do know is that this study could be a breakthrough for the many, many mothers looking to give birth via IVF.

[Stanford University]



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