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Pregnancy delayed: Why freezing your eggs is a crummy insurance policy

Health Advisor is a regular column where contributors share their knowledge in fields ranging from fitness to psychology, pediatrics to aging. Follow us @Globe_Health.

Aren't we all trying to slow, if not stop, the biologic clock? Many of us are doing brain exercises, building muscle at the gym, injecting our lips with fillers, and colouring our hair to cover the grey. Most of these anti-aging behaviours seem to start in our 40s, around the time we realize that 40 really isn't the new 30.

For our eggs, we should be thinking about the effect of age a decade or two before we think about our thinning lips and grey hair, as eggs are in a short and vanishing supply as early as our mid-30s. That's right, by the time you are trying to yoga-yourself-young, your eggs are nearly done. Can you stop the biological clock? The good news is you sort-of can by freezing your eggs.

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The first successful freezing and thawing of human eggs to achieve a pregnancy occurred in 1986. Over the following two decades thousands of women froze their eggs, hoping to be able to use them when they were older to have a child, but very few had success. Then came vitrification. Vitrification is a "fast-freezing" technique that causes less damage to the eggs so they are far more likely to achieve a pregnancy after they are thawed.

This is great news for women who are running out of eggs for medical or social reasons. Medically, women who are diagnosed in their 20s or 30s with cancer often have not had children yet. The treatment of their cancer, particularly chemotherapy, can destroy many or all of their eggs. Freezing eggs prior to cancer treatment gives them a chance to have a child using their eggs in the future. It's not just cancer treatment that can destroy eggs. Several genetic conditions, such as Turner syndrome, cause women to run out of eggs rapidly in their teens and 20s. These women may also benefit from freezing their eggs.

Socially, more and more women are delaying pregnancy in the interest of their career, relationship, finances or for other reasons. Instead of chemotherapy or genetics eroding their egg supply, time is eroding their chances of conceiving. These women can freeze their eggs when they are abundant and healthy, say in their 20s, for use when they are ready to conceive late in life, say in their late 30s or 40s.

Egg freezing for medical or social reasons is truly stopping the biologic clock. A typical egg freezing treatment involves a woman taking injection of hormones for 10-14 days. The hormones help her grow many eggs at once. Once the eggs are ready, as judged by their appearance on ultrasound and hormone levels, they are removed through the vagina, cleaned up and frozen by vitrification. Eggs can be frozen for years, and a typical woman in her 20s or early 30s may expect to get 10-20 eggs to freeze at a cost of about $5,000. Then, one day in the future, when she is ready to be pregnant, the eggs are thawed, fertilized with sperm to create an embryo and the embryo is put into her uterus with the hope of achieving a pregnancy.

Why doesn't everyone rush out and freeze their eggs in their 20s and 30s, just in case their eggs aren't abundant or healthy enough when they need them? What's the catch? There is no guarantee that you will have a child from frozen eggs. The success rate is between 4 and 12 per cent for each frozen egg, depending on a woman's age and health at the time the eggs are frozen. The success rate drops even lower after age 40. Egg freezing may give a woman false hope and even encourage her to delay childbearing when she shouldn't. As I say to my patients, egg freezing is like crummy insurance policy – you pay now but there is no guarantee it will pay you in the future.

Despite the ethical concerns, particularly with social egg freezing, many fertility clinics in many countries are marketing social egg freezing to women who wish to have children but aren't ready just yet. Some countries are even considering public funding for egg freezing.

The science, the clinics and the many women are ready to embrace egg freezing, are we?

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Dr. Beth Taylor is co-founder and co-director of Olive Fertility Centre ( and in Vancouver. She is a Clinical Associate Professor at UBC and co-ordinates the UBC Obstetric & Gynecology residency program "Reproductive Endocrinology & Infertility" rotation. She is an active staff member at BC Women's Hospital and Vancouver General Hospital and performs surgery at both of these centres.

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