Egg Freezing: 5 Things You Need to Know
Credit: Stockxpert

The announcement that Apple and Facebook will cover the steep cost of egg freezing for their employees has many people talking about the risks and benefits of the procedure.

Last week, Facebook said it has already started covering egg freezing, and Apple plans to add the benefit next year. Both companies said they would cover up to $20,000 of the cost of the procedure, which can range from $5,000 to more than $15,000, not including the cost of the required medications, which can be thousands of dollars more.

Egg freezing is viewed as a way to thwart a "ticking biological clock" — as women grow older, it becomes more likely that their eggs will have chromosomal abnormalities, which increases the risk of miscarriage and certain disorders, and can make it harder or impossible for women to conceive. [Future of Fertility Treatment: 7 Ways Baby-Making Could Change]

But egg freezing is not a perfect fix. Here are five important facts to know about egg freezing.

Egg freezing is better now than it used to be

Egg cells contain a lot of water, and so when they are frozen, crystals can form that damage their structure. For this reason, the egg-freezing techniques of the past were not as successful as current ones, and were used mainly by women with cancer or other conditions who faced a high risk of losing their fertility from chemotherapy.

A new technique has come around in the last five years, which freezes egg cells so quickly that the crystals do not form. Studies have found that eggs frozen with this new technique, called vitrification, are similar to fresh eggs in their ability to lead to pregnancy (if the eggs are taken from a woman still at a young age). Because of these findings, the American Society for Reproductive Medicine (ASRM) declared egg freezing no longer experimental in 2012.

But it's still not recommended for delaying childbearing

The ASRM now recommends egg freezing for several groups of people, including women who may lose their fertility during chemotherapy. The procedure is also recommended for couples who are undergoing in vitro fertilization (IVF) and are not able to fertilize eggs the same day that they are collected (because sperm from the male partner is not available on that day), and for couples undergoing IVF who have surplus eggs and do not wish for those eggs to be fertilized and frozen as embryos.

However, there is not enough data to recommend that women freeze their eggs for the sole purpose of delaying childbearing, according to the ASRM. Studies are needed on the safety, efficacy, cost effectiveness and emotional risks of the procedure for this purpose, the ASRM said.

"Marketing this technology for the purpose of deferring childbearing may give women false hope and encourage women to delay childbearing," a 2012 report from the ASRM said. "Patients who wish to pursue this technology should be carefully counseled about age and clinic-specific success rates of oocyte cryopreservation vs. conceiving on her own, and risks, costs, and alternatives to using this approach."

Freezing your eggs means a lot of trips to the doctor

There are three main steps to egg freezing: stimulation of the ovaries, retrieval of the eggs and egg freezing.

For the first step, women are given hormones to stimulate their ovaries to produce multiple eggs in one cycle. During this phase, women visit the doctor frequently — sometimes five or six times over a two-week period — to monitor how well the treatment is working. At these visits, doctors view the ovaries with a vaginal ultrasound to look at the maturing eggs, and take blood samples.

In general, it takes about eight to 14 days of hormone treatment before the eggs can be retrieved, according to the Mayo Clinic.

Eggs are retrieved from the ovaries with a suction device that is connected to a needle. Ultrasound is used to guide the needle through the vagina to the egg follicle, according to the Mayo Clinic. The procedure is done under sedation.

During the actual egg freezing, eggs are cooled to subzero temperatures, the Mayo Clinic says.

Egg freezing at younger ages is best

Frozen eggs can later be thawed, fertilized and implanted using IVF.

But the chances for success (pregnancy) are greater if a woman uses "younger" eggs — meaning either eggs she froze in her 20s or early 30s, rather than later on, Dr. Wendy Vitek, a fertility expert at the University of Rochester Medical Center, told Live Science in an interview in June.

"The power in egg banking is that it allows women to have the freedom to keep looking for the right partner, and alleviates that stress that occurs when a woman is in her late 30s and early 40s and hasn't quite found the right person," Vitek said.

Egg freezing is not a not a guarantee for pregnancy

However, a woman who freezes her eggs, even at an early age, still does not have a guarantee for pregnancy later in life. Studies conducted in Europe on frozen (vitrified) eggs from donors under age 30 found that women's pregnancy rates ranged from 36 to 61 percent.

And an online fertility calculator developed by researchers at New York Medical College and the University of California Davis estimates that a woman who freezes 15 eggs at age 30 has about a 30 percent chance of giving birth to a child if she uses these eggs. A woman who freezes 25 eggs at age 30 has about a 40 percent chance of giving birth to a child, the calculator estimates.

Natural pregnancy rates are not 100 percent, either; among couples without fertility problems, 60 percent will become pregnant within three months of trying.

Follow Rachael Rettner @RachaelRettner. FollowLive Science @livescience, Facebook & Google+. Original article on Live Science.