More women are freezing their eggs, but not all eggs survive the thawing process. Here's why that happens.

For decades, those hoping to become pregnant have turned to doctors to freeze their eggs in a process called oocyte cryopreservation with the intention of using their eggs at a later time. Though the first reported human birth from frozen eggs occurred in 1986, it wasn’t until 2012 that the American Society for Reproductive Medicine declassified the procedure as experimental. Since then, the process has become very popular, but that doesn’t mean it always yields the desired results. According to UCLA Health, successful pregnancy rates from egg freezing are estimated to only be between 4-12% per oocyte. The reasons vary, but one crucial moment during which the eggs become unviable is when they are thawed.

Ahead, women whose frozen eggs didn't survive the thawing process share their experiences — and what they wish they'd done differently.

What it's like when your eggs don't survive thawing

Dr. Kristina Kasparian, a ​​writer and brand consultant in Montreal, says egg freezing was recommended to her when she was 28 and showing signs of perimenopause and endometriosis. She went to a fertility clinic for help.

“They realized I had an extremely low ovarian reserve and recommended that I freeze my eggs to preserve my fertility,” says Kasparian. She was married but wasn’t ready to have kids at the time. “I agreed to the IVF protocol that the doctor recommended and we ended up with five eggs to freeze,” she says.

Kasparian and her husband decided to finally use the eggs four years later.

“The embryologist called us to tell us that only two eggs survived the thaw,” says Kasparian. She didn't understand why it had happened, or why the clinic didn’t offer the option of freezing embryos, which have a better success rate, instead. “Both were fertilized, but only one resulted in a viable embryo which, sadly, I eventually miscarried,” she says.

Kasparian felt angry, in part because she says the clinic did not make it clear that this was a possibility. “We always knew some may not fertilize, but I never expected that some may not even make it through the thawing process,” she says.

Elizabeth King, founder of the Fertility Coach Academy in Orange County, Calif., decided to have 13 of her eggs retrieved when she was 36 and single. Of those, 11 eggs were healthy enough to freeze. At age 43, she decided it was time to try and use them.

“I was now married and had two children, but had also suffered from having miscarriages,” says King. Of the 11 eggs, eight didn’t survive the thaw. Her remaining three eggs did not result in a pregnancy.

King wound up going to a different clinic in Newport Beach, where she was given Letrozole, an oral drug which can stimulate ovulation and follicle production. She was thus able to conceive naturally and have her third baby. While this can be an option for some individuals and couples, others who may have had to freeze their eggs for other reasons, like undergoing cancer treatments, or who cannot conceive without assistance, are left with little recourse.

Why do frozen eggs not always make it through the thaw?

Dr. Ruth O. Arumala, co-chief medical officer at Zuri Fertility, says there are many factors to consider when it comes to egg freezing and thawing, including the way the egg was frozen and the skill of the lab.

“‘Slow freezing’ was the standard technique in the past, and only about 60% of eggs survived the thawing process,” says Arumala. “However, ‘flash freezing’ techniques can lead to success rates of over 90%. This is a newer method.”

Arumala adds that there is currently no way to test the quality of a person’s eggs at the time they freeze them.

“The only testing done is to see whether or not the eggs are mature enough for freezing,” says Arumala. “This is in contrast to frozen embryos, which have gotten to a point where they can be graded on quality before they are frozen.”

Additionally, she reminds potential patients that the frozen eggs have to undergo many steps to result in a live birth, from thawing, fertilization and embryo growth, to transfer, implantation and then, hopefully, a healthy pregnancy. During these steps, doctors might find a number of issues that contribute to the unviability of the egg or embryo.

“There may be problems with the quality of the eggs that are found during the implantation and/or growth stages that lead to issues with embryo development,” says Arumala. “For example, there may be genetic defects in the egg that make it harder or impossible for a healthy embryo to grow.”

So does that mean freezing fertilized eggs (a.k.a. embryos) is better?

It depends.

“In the past, embryos had much higher rates of successful thawing than eggs. This is because eggs have a larger percentage of water within the cell, which can lead to the formation of ice crystals that can damage the eggs,” Arumala explains.

“However, the best labs have gotten much better at freezing and thawing eggs, in a process known as vitrification, and some have success rates of thawing that are similar to that of embryos,” she says.

What can patients do to improve their odds?

Arumala recommends asking labs ahead of time for specific statistics, as this can vary from lab to lab, though she warns that pregnancy isn’t guaranteed even if the egg freezing process is successful.

Beth Gulotta, psychotherapist and founder of NYC Therapeutic Wellness, also advises potential patients to find a clinic and/or doctor that creates a more personalized experience that makes them feel seen, heard and really cared for.

“Some women have [reported] that their experiences throughout the egg freezing process has felt really impersonal and like they are on a conveyor belt,” says Gulotta, adding that clinics that really sympathize with patients will make them feel supported.

How can egg freezing patients handle these losses?

“Egg freezing is such an emotional process overall whether you get viable eggs or not. However, hearing the news that your eggs have become unviable can bring feelings of despair, hopelessness and great sadness and grief,” says Gulotta, who also hosts Quiet The Clock, a podcast about navigating fertility, relationships and career changes. She recommends anyone starting this journey to have a solid support system to lean on.

“Let yourself be in your feelings and be compassionate and kind to yourself. It is very common that women will quickly blame themselves or their bodies for failing them, and this is not helpful,” she says.

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