Recently, I had lunch with a young female lawyer and we began to talk about her strong desire to have a child. In her mid-thirties and not in a relationship, she expressed fear that she might not meet a partner until it was too late. It did not take long for me to realize that the thought of freezing her eggs had not crossed my lunch companion’s mind. It occurred to me that if a woman like her (living in a major metropolitan city, professional, unmarried, in her mid-thirties, and certain that she wanted children), wasn’t thinking about taking steps to preserve her fertility, egg freezing still does not have the full attention of women who might want to consider it.

Until recently, egg freezing was not a particularly realistic option for women. It was not that efforts to freeze eggs were not being made; they certainly were. The problem was with the “slow freeze” approach to freezing eggs, which caused ice crystals to form and damage the cell. Egg freezing recently became a more realistic option when a technological advance called “vitrification” improved the process, preventing ice crystal formation. As recently as October 2012, the American Society for Reproductive Medicine removed the “experimental” label it had placed on egg freezing in 2008, and emphasized that in young patients the outcome with egg freezing is comparable to the outcome in IVF cycles using fresh eggs. This was an exciting moment in the world of assisted reproductive technology. It was also an important moment for women because it broadened their reproductive choices in a dramatic way.

The realities of female reproductive biology are inescapable. A woman is born with a finite number of eggs. They are depleted throughout her lifetime and as they decrease in number, their quality also diminishes. A significant proportion of the eggs that remain in an older woman’s ovaries become genetically abnormal and incapable of producing a healthy baby. If a woman freezes her eggs when they are still plentiful and genetically normal she will improve her odds of having a healthy baby should she find herself in a position to become a mother only after her reproductive prime is behind her.

The younger a woman is when she freezes her eggs, the greater the likelihood that she will succeed in having a baby with them. A very good time to freeze eggs is when a woman is in her late twenties or early thirties. Once they are frozen, a woman’s eggs are suspended in time and can last for decades and probably longer. For example, a woman who freezes her eggs at age thirty, is preserving her thirty year old reproductive potential.

Although it is most promising for a woman to freeze her eggs when she is still relatively young, most fertility clinics are not turning away women who are older. They agree that older women are better off freezing their eggs than simply hoping to soon meet a partner. It has been reported that the current average age of women inquiring about freezing their eggs is 38.

Women who decide to freeze their eggs should be careful when choosing a fertility clinic in which to do so. There is a lot of hype and marketing around egg freezing, especially in large urban centers where it is most common. Surprisingly, some fertility clinics are still using the “slow freeze” method of freezing eggs. And even in clinics that are using advanced vitrification techniques, many cannot point to a statistically significant track record of successfully thawing frozen eggs, creating embryos with them, and then conducting transfers that have resulted in the birth of a baby. As a result, a great deal of research and analysis should be undertaken before deciding on a clinic.

Finally, it is important that women who freeze their eggs understand that frozen eggs are not a 100% guarantee of a baby; they are merely the hope of a baby. Some eggs may not survive the vitrification and warming process, some may not fertilize, and some embryos do not implant. In making choices about how to conduct their lives after freezing their eggs, women ought to consider how they will feel if their frozen eggs do not result in a child.