Putting life on ice

MARY REICHARD, HOST: Coming up next on The World and Everything in It: freezing human embryos.

No one knows exactly how many human embryos are currently frozen in the US. Estimates range from a few hundred thousand tomore than a million.

NICK EICHER, HOST: Alabama’s Supreme Court made a ruling last year that brought these tiny frozen humans into the national spotlight. It classified them as children under a civil wrongful death law, sparking discussions about IVF both among lawmakers and the general public.

REICHARD: In recent episodes of our Doubletake series, WORLD’s Leah Savas explained the process of IVF from the perspective of a mom who used it. Today, we’ll hear from a former embryologist who explains what embryos go through.

LEAH SAVAS: Craig Turczynski has a PhD in reproductive physiology and used to work as an embryologist in an IVF lab. He left embryology more than 20 years ago over ethical concerns.

CRAIG TURCZYNSKI: The final straw was actually when I was … essentially forced to discard a patient's … embryos. Patient wanted them discarded. The patient's physician, who was my boss insisted that I follow the patient's wishes.

It’s standard in the field to discard embryos if they are deemed low quality or if they’re simply unwanted. Many Christians see IVF as acceptable to pursue as long as they avoid discarding their embryos and commit to using all of them, even if it means some of the embryos have to remain frozen for a time.

But, as Turczynski explains, even the standard process of freezing embryos has its own ethical complexities.

TURCZYNSKI: The fact that they're even created and then frozen … doing that is never for the benefit of the embryo itself. It's only to improve the opportunity that at least one of them will become a baby for the parents. So it's a benefit to the parents, it's a benefit to the program, because they do want success, but it's at the expense of these human lives.

Usually in the IVF process, providers inseminate more eggs than they intend to immediately transfer into a woman’s uterus. This is to increase the chances of having multiple viable embryos to work with.

TURCZYNSKI: After they select the embryos that they would transfer, then the remaining embryos that they call excess, … they have to first put them in a medium. A liquid medium that they call a cryo protectant.

That essentially dehydrates the embryo, replacing the water inside its cells with the cryoprotectant substance. It helps prevent the formation of ice crystals in the cells.

TURCZYNSKI: The enemy of any cell that's being frozen is the formation of ice crystals, which would be like internal knives that go in and basically lyse cells and kill them.

The amount of water the lab removes from the cells depends on the freezing method used. The most common method today, called vitrification, is a fast-freezing technique that involves using more cryoprotectants and then plunging the embryos into liquid nitrogen so that their temperature drops hundreds of degrees fahrenheit in seconds. That puts the embryo into a glass-like state, effectively eliminating ice crystal formation, if done correctly.

TURCZYNSKI: So even though they're subjected to this cryo protectant, it doesn't 100% protect them, right? Some survive. Some don't. Usually the more viable ones will survive.

While the fast-freezing technique is safer for the embryos than an older slow freezing technique, the substances used as cryoprotectants in both methods can be toxic to cells.

TURCZYNSKI: The cryo protectant itself is not in any way therapeutic to the embryo. ... It's the better of two evils, right? If you don't use any cryo protectant, it's definitely going to die, but it's not … a benefit to the embryo at all, but it helps it survive this process.

Now in a glass-like state, these embryos have a new home, inside of metal tanks filled with liquid nitrogen. Metal canisters hang in the tanks, suspended from hooks. Each canister contains smaller metal devices called canes, which hold even smaller plastic devices, straws or vials, that contain the microscopic embryos.

When a patient is ready for one or more of the frozen embryos, the lab removes the embryos they want to use. They have to warm them up from the sub-zero temperatures and replace the cryoprotectant with water… all at the right speed to avoid damaging the embryos.

TURCZYNSKI: You don't want so much water to rush into the embryo that it explodes it and that is one of the harm that's one of the things that can happen to that embryo, is it can basically explode. So you look under the microscope, all you see is fragments of an embryo, or you may not see anything at all.

While most embryos survive vitrification, up to 5% don’t. But even when all of that goes right, there’s still a lot more that can go wrong with embryos that parents entrust to fertility centers.

SAVANNAH GUTHRIE: The case involves couples whose embryos were destroyed when a patient removed them from a freezer and accidentally dropped them.

KAI REED: The storage tanks containing liquid nitrogen to keep the material at a certain temperature failed. In Cleveland that means over 2,000 eggs and embryos were compromised. A similar problem occurred at a facility in San Francisco the same weekend.

GAYLE KING: A married couple is suing a fertility clinic and its owner over an IVF mixup that led two women to give birth to the other person’s baby.

Stories like these are rare. But they don’t surprise Turczynski. And they just reinforce the reasons why he no longer supports the process.

Nationally, Turczynski’s views are certainly in the minority. A Pew Research Center poll in April 2024 found that about 70% of Americans see IVF access as a good thing. Even among people who believe life begins at conception, around 60% see IVF positively, according to the same survey. For them, the focus is on the children who would not have otherwise been born—not the plight of the embryos on ice.

And for Turczynski, that’s the whole point. The focus of IVF is on the final product instead of how the process affects people—including frozen embryos.

TURCZYNSKI: This is my personal belief, right? It's part of the reason why I left, is that it's only because you're doing these things that you set up scenarios that really can't be solved, right? And you set up scenarios that are absurd … and you couldn't make them up.

Reporting for WORLD, I’m Leah Savas.

WORLD Radio transcripts are created on a rush deadline. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of WORLD Radio programming is the audio record.