A new report is showing that frozen eggs are significantly less likely to lead to successful in-vitro fertilization. According to this report, the use of frozen eggs lead to a live birth approximately half of the time. In comparison, the odds of a live birth when using fresh eggs were about 19.1% higher.
The report in question was authored by Dr. Vitaly Kushnir and his colleagues at the Center for Human Reproduction in New York. It takes into account statistics from more than 11,000 different instances of IVF treatment. The data reflects every instance of IVF involving donated eggs which was reported to the Society for Assisted Reproductive Technology in 2013, which is the most recent year for which SART has complete and collated data available.
Approximately 20% of the 11,138 IVF cycles analyzed in the report involved previously frozen eggs. The rest were live embryos, which were implanted as soon as they were retrieved. Dr. Kushnir's report has since been published in the American Medical Association's Journal of Internal Medicine.
The report by Dr. Kushnir and his colleagues is a statistical measurement. While the indicated result seems fairly clear, the reasons behind it are not. The specific cause for the relative lack of vitality in previously frozen eggs is beyond the scope of the report. At the same time, the inherent implications may spell trouble for the future of this highly touted technology.
When the technique of freezing embryos for future use was first put into practice in 2010, after twenty-five years of IVF treatment using fresh eggs exclusively, it was widely advocated as an “insurance policy.” A businesswoman in her early twenties could have her eggs harvested and successfully fertilized, then frozen for use years – or even decades – down the road. After completing her education, or reaching a professionally comfortable stage in her life, she might then choose to have children . Frozen eggs provided a way to halt the biological clock, and to provide for the possibility of a family using a woman's own genetic offspring – at a time when it was most convenient.
Egg freezing was seen as a way to help encourage more women to pursue advanced degrees, to enter the workforce as highly-skilled professionals, and to round out their lives with the ability to pursue their passions – such as travel, or opening small businesses – all while putting family life “on hold.” If the technology should prove to have a relatively low ceiling for viability, however, it will call this potential application into question. Even with fresh eggs, it is not unheard of for some women to attempt pregnancy through IVF several times before it works. If a woman is in her late thirties or early forties, and facing a narrow window of convenience for starting a family of her own, less viable embryos would run the risk of making this option impractical for her.
When it comes down to recommendations for the future of frozen eggs in IVF, Dr. Kushnir is personally hesitant to make any profound statements. He explains that the scope of the report falls short of explaining the reduced viability of frozen eggs.
At this point in time, most experts are in agreement that additional research is needed. The use of frozen eggs in IVF is simply too recent an innovation for any long-term evaluations to be made using significant amounts of data. For example, many genetic conditions affect so few children overall that a measurement taken from the small number of live IVF births would not yield enough information to be significant.
Dr. Kushnir cautions against leaping to conclusions, but he does make the recommendation that intended parents be informed, in writing, as to the reduced viability of IVF treatment using previously frozen eggs. It has also been suggested that intended parents choosing to pursue IVF treatment using previously frozen eggs should be required to sign off on their understanding of its potentially reduced viability.
It is encouraging to have another means of family building. However egg donation cycles with fresh donor eggs are likely to remain a prominent and very successful method, particularly as the rate of live births in response to such treatments continues to increase. For those not willing to accept lower success rates, an IVF transfer with fresh eggs leads to the strongest chance of delivering a baby – the ultimate goal for all intended parents.