Recent Progress In Egg Freezing

By Fady I. Sharara, MD, FACOG

Virginia Center for Reproductive Medicine

More Complementary & Integrative Healthcare Articles

Recent Progress In Egg Freezing

Although sperm and embryos have been successfully frozen, and subsequently thawed to create healthy children for over 20 years, it is only recently that successful egg freezing has become a reality. There are two primary groups of women who are likely to benefit from egg freezing 1) women who are at risk of becoming sterile due to chemotherapy for cancer, and, 2) women who want to delay a pregnancy until later in life but who hope to retain their current reproductive potential. It is the latter indication that holds the most promise for career-oriented women who are not yet ready to start their family building.

The attraction for egg freezing in the latter group is based on basic biology of reproductive aging. Women are most fertile during their late teens and 20s, and for most women, getting pregnant becomes somewhat more difficult by their mid-30s, mainly because the number and quality of eggs decreases as women age.

Studies have shown that by age 37, eggs decrease in quality and numbers more quickly, and becoming pregnant becomes more difficult. By the time women reach the age of 43 or 44 their chances of becoming pregnant are drastically reduced, about 1-2% even with the most aggressive therapy. Unfortunately, most of the callers to our center inquiring about egg freezing are women in their early to mid 40s, a time when very few good eggs are left. The ideal candidates for egg freezing are women in their 30s. Also, any woman recently diagnosed with cancer needs to look at this option seriously before starting chemotherapy.

It has been 22 years since the first successful pregnancy was reported from frozen and then thawed eggs, however only a handful of births were reported over the next decade. Today, over 200 babies have been born using this technology. A survey of recently published literature yields pregnancy success rates ranging from 30-40% per embryo transfer.

Slow freezing is the most commonly used method to freeze eggs, and is the method that has resulted in the vast majority of babies born from frozen oocytes worldwide. Slow freezing methods, with only slight modifications, are based on the procedure first described nearly 30 years ago. Ultra-rapid freezing, or vitrification, literally achieving a glass-like state, is now the state of the art method of egg freezing and the one currently employed at our center.

In the fall of 2004, The American Society for Reproductive Medicine (ASRM) issued an opinion on oocyte cryopreservation concluding that the science was “promising” due to the fact that recent laboratory modifications have resulted in improved egg survival, fertilization, and pregnancy rates from frozen-thawed oocytes in IVF. The ASRM noted that from the limited research performed to date, there does not appear to be an increase in chromosomal abnormalities, birth defects, or developmental deficits in the children born from frozen eggs. There have been numerous reports over the past several years attesting to the safety of this technique in clinical practice.

Effective egg freezing provides exciting new opportunities to many women. Based on the recent advances and encouraging results, new applications for egg freezing will continue to emerge, and its wide-spread acceptance as a mainstream technology may be around the corner.