Freezing your eggs for the future

 

How to Freeze an Egg

Vitrification is an ultra-rapid cooling technique used today to preserve a woman’s oocytes (eggs) and embryos. Vitrification and storage of eggs, also known as fertility preservation, begins with a 10- to 12-day process of controlled egg growth and maturation before the eggs are collected from the woman’s ovary.

Processing eggs for vitrification involves removing water from inside the egg using solutions of concentrated sucrose (sugar) and cryoprotectants that act like antifreeze.

The sugar aids in drawing the water out of the egg by simple osmosis and the cryoprotectants replace the water and protect the egg from the effects of ultra-rapid cooling.

The egg, which is only about a tenth of a millimeter in diameter, is placed on a storage device that resembles a tiny coffee stirrer. When it is plunged into liquid nitrogen, the ultra-rapid cooling occurs at a rate of more than a thousand degrees per minute. This eliminates any risk of ice crystal formation that would damage the egg.

The entire process from fresh to vitrified egg takes about 10 minutes. Vitrified eggs are stored in liquid nitrogen at a temperature of minus 196 degrees Fahrenheit. For long term-storage they are transferred to a specialized facility.

When the time comes for the woman to try to get pregnant, the vitrified eggs need to be warmed as rapidly as they were cooled to, once again, avoid damage by ice crystal formation inside the egg.

This is accomplished by rapidly transferring the vitrified eggs from storage in liquid nitrogen to a sucrose solution at body temperature (98.6 degrees F). The rehydration of the egg must be carefully regulated so the egg doesn’t swell too quickly and burst like a balloon.

Once they have regained their water content, the eggs are left in a culture medium for three hours during which time they recover their cellular functions. After that, the eggs are fertilized using a sperm injection method (ICSI) and then cultured for five days.

After they reach the blastocyst stage, one or two of the embryos are transferred into the woman’s uterus in the hope that pregnancy will continue to term.

Source: Dr. Jeffrey Knickerbocker at Fertility and IVF Center of Miami.


Special to The Miami Herald

Jennifer Anniston, Kim Kardashian and Dancing with the Stars pro Karina Smirnoff are thinking ahead. They are drawing attention to the trend of cryopreservation or freezing their eggs in order to preserve fertility into their 40s.

“It’s a progression,” says Dr. Michael Jacobs, medical director of the Fertility and IVF Center of Miami located on the campus of Baptist Hospital.

You are most fertile in your 20s, then between 35 and 38 things “go downhill.” After age 42, it’s very difficult for a woman to get pregnant with her natural eggs.

“And once a woman reaches 43, 44 or 45, it’s very rare to be successful using that patient’s fresh eggs,” he says.

Yet more and more women are waiting to have babies. According to the Centers for Disease Control and Prevention (CDC), first birth rates for women aged 40 to 44 increased steadily in the United States from 1990 to 2012.

“You can try to outsmart the ovary with fertility drugs. But the way to really fix the fertility problems that come with age is to think ahead of the game and to think about fertility preservation,” says Jacobs.

Up until two years ago, egg freezing was considered an experimental procedure recommended only for those with medical conditions such as young cancer patients scheduled to undergo chemotherapy. By preserving their eggs before their treatments, they had a better chance of being able to get pregnant with their own babies later in life.

However, over the past five years the vitrification technique of freezing has been improved to the point that it is no longer considered experimental.

So women who are not ready to have children by the time they are 35 can have their eggs harvested and frozen with relative safety.

When they are ready to get pregnant, they can try to do it naturally. But if a natural pregnancy doesn’t occur, these woman will have her young eggs in cold storage so that they can be thawed, fertilized by in vitro fertilization (IVF) and then implanted.

If at 41 you get pregnant with the eggs that were frozen at age 31, your potential to have a successful pregnancy is about the same as that of a 31-year-old, providing you have a normal uterus.

“It’s like having your own personal egg bank,” says Jacobs.

But prescribing this technique for healthy young women who merely want to put off having a baby while they pursue a relationship, a career or a lifestyle, is considered somewhat controversial.

Dr. Samantha Pfeifer, chair of the American Society of Reproductive Medicine Practice Committee says, “Based on available data, we cannot endorse the widespread elective use of egg freezing to delay childbearing.”

She insists there needs to be more data to determine the success rate in older women, the appropriate age for egg freezing, how many eggs ideally should be frozen and for how long the eggs can be kept frozen and still produce a viable pregnancy.

For a young woman who wants to have children in the future, it can be a difficult decision.

“That’s why she needs to know the pros and cons,” says Dr. George Attia, director of the division of Reproductive Endocrinology and Infertility at the University of Miami.

The longer a woman lives, the more time there is for problems and complications to develop that could affect her ability to be pregnant.

“There are a lot of environmental, chemical, hereditary, age and biological factors that can impact the ability of a woman to have good eggs,” says Dr. Jeffrey Knickerbocker, clinical laboratory director for the Fertility and IVF Center of Miami.

For example, if you dye your hair or smoke for 20 years, that may affect the quality of your eggs. And conditions such as endometriosis, fibroids, diabetes, high blood pressure, rheumatic diseases, lupus and arthritis may decrease your chances of having a successful pregnancy.

Also, as a woman and her eggs get older, the chances of chromosomal abnormalities increase. And chromosomal problems can lead to miscarriages or live births to babies with Down syndrome. The risk of a woman giving birth to a live baby with Down syndrome is about one in 350 at age 35; by age 40 it is one in 100.

But it’s the age of the egg, not the age of the uterus, that determines if you are going to get pregnant and what your miscarriage rate due to genetic issues will be, Jacobs says.

That’s why some doctors are recommending that healthy women who want to be mothers but reach 35 without wanting to become pregnant, should freeze at least one cycle of their eggs.

The process itself takes preparation, including prescreening for infectious diseases and then injecting hormones for 10 to 12 days. During this time, a woman visits her doctor’s office four or five times for ultrasounds and blood work to monitor her progress.

The eggs are removed under intravenous sedation — much like the anesthesia used for a colonoscopy. Then the eggs are sent to the laboratory where they are frozen using a process called vitrification or cryopreservation (see box) before being transported to long-term storage.

Then there is the expense. Harvesting, freezing and transferring one cycle of eggs to a long-term storage facility can cost $7,000 to $10,000. The drugs required for these procedures costs about another $4,000. And it can cost from $200 to $400 a year to store the eggs.

One cycle of eggs may not be enough. Depending on her age, a healthy woman produces 10 to 20 eggs in a cycle. Doctors recommend women in their 30s freeze about 20 eggs.

“The more eggs you freeze, the higher the probability you eventually are going to get pregnant,” says Attia. But of course, freezing two cycles almost doubles the cost.

Then when it is time to try to get pregnant, the eggs need to be thawed and fertilized before they are implanted in the uterus. These procedures can cost $5,000 to $7,000 plus a lot of emotional outlay because there is no guarantee of success.

“I think freezing eggs to preserve your fertility is a good option as long as you understand the implications of doing it,” says Attia.

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