fbpx Choosing Between Egg Freezing and Embryo Freezing

Fertility - Assisted Reproductive Technology | January 5, 2022, 10:38 CST

Choosing Between Egg Freezing and Embryo Freezing
The differences between these two procedures may help you decide which is right for you.
Illustration by Tré Carden

When Sami Sage, the founder and chief creative officer of Betches, a female-founded media brand, began documenting her embryo-freezing journey, her followers had many questions and accolades for Sage's transparency. People thanking Sage for her honesty, and questions about every detail of the process filled the comment section of the Instagram post.

It seems that many people are somewhat familiar with egg-freezing, which has become extremely popular in recent years.

"In 2017, 10,936 women froze their eggs—23 times more than women did in 2009," states a 2017 study published by the Society for Assisted Reproductive Technology (SART).

Embryo-freezing, on the other hand, is not a procedure people have heard as much about. One reason for this? Women simply undergo egg-freezing more than embryo-freezing.

'Embryos are much further down the funnel and therefore offer more concrete prognostic information in terms of a chance at live birth.'

"I believe that women are opting to freeze their eggs in greater numbers than the other modality of embryo freezing," confirmed Kecia Gaither, M.D., double board-certified physician in OB-GYN and Maternal-Fetal Medicine.

Both egg freezing and embryo freezing have benefits. For individuals or couples, choosing one over the other is based on their personal goals and stage of life.

"Egg freezing and embryo freezing essentially begin the same way," Gaither explained. "Hormones are given to the woman to stimulate the ovaries to produce multiple eggs." From there, the processes diverge.

Below, learn more about both of these fertility preservation options and how to choose the procedure that's best for you.

What is egg freezing?

Women inject themselves with hormones between one and three times per day for around two weeks to stimulate the production of unfertilized eggs (which are called oocytes). Typically, women also stop taking birth control at least one month before the injections to ensure maximum effectiveness from the hormones.

Then, the doctor retrieves the eggs by inserting a needle into the ovarian follicles and using an ultrasound to guide them. The eggs are frozen right away for up to 10 years on average.

"Once the eggs have been harvested from your ovaries, they are assessed for maturity. Usually, around 80 percent will be mature. Because only mature eggs can be fertilized, we only freeze the mature eggs," explained New York Spring Fertility doctors, Shefali Shastri, M.D., medical director, and Kolbe Hancock, M.D., fertility specialist.

"When you come back to utilize the eggs, around 85 to 90 percent will survive being thawed, and of those that thaw, approximately 75 percent will fertilize successfully," Shastri and Hancock added.

From there, eggs can be combined with sperm in a lab after developing for five days. Then they can be genetically tested or transferred to your uterus through in-vitro fertilization (IVF).

"Once the egg has been fertilized by a sperm, it is called an embryo," Shastri and Hancock said. "But each egg does not guarantee an embryo and each embryo does not guarantee a live birth."

What is embryo freezing?

After embryos are developed from the combination of fertilized eggs and sperm via IVF, they can be frozen.

"The rate of conversion from mature eggs to embryos is around 40 percent, and the percentage of embryos that are genetically normal is dependent on age but ranges from about 75 percent at age 28 to about 25 percent at age 42," Shastri and Hancock said. "Each genetically normal embryo, when transferred back into the uterus has approximately a 60 percent chance of live birth."

After frozen embryos are thawed, women can prepare their uterus for a frozen embryo transfer by injecting themselves or taking estrogen/progesterone pills.

Why would someone freeze their embryos?

"Embryos are much further down the funnel and therefore offer more concrete prognostic information in terms of a chance at live birth," Shastri and Hancock explained.

Additionally, there is more data on usage and thaw rates for embryos. Seemingly, embryos survive the thaw slightly better than oocytes (about 95 percent versus 90 percent).

Women may decide to freeze their embryos if they already have a partner and want to preserve the option to have kids with that specific person in the future. It can be a good option for couples who know they want children but need more time.

However, because embryos are made of genetic material from the egg and the sperm, they are considered joint property. Both parties need to agree to parenthood before any embryos are transferred.

"With frozen embryos, legal implications can ensue," Gaither said, "particularly if the partner utilized to fertilize the egg is no longer in the picture during the time a woman wishes to have a family with someone else, or if there is a desire from one person to discard the embryos while the other wishes to keep the frozen embryos."

Why would someone freeze their eggs?

"Eggs are further up the funnel of attrition and offer less prognostic data in terms of live birth," Shastri and Hancock said.

However, eggs belong only to the female partner, which preserves future parentage options. "There exists a level to preserve fertility independently and maintain reproductive autonomy," Gaither explained.

Women may freeze their eggs if they're not ready to have children or don't have a partner yet to have kids with. They may also have a medical condition that could affect their ability to conceive naturally and want to freeze their eggs so they can still get pregnant later on.

But remember, there doesn't need to be a medical or fertility-related reason to freeze your eggs or embryos. It can be a way of taking control of your reproductive system and giving yourself time to decide what you want.

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