Oocyte Preservation aka Egg Freezing – Ready or Not, It’s Here

Oocyte preservation, or egg freezing as it is popularly called, is now being offered by over half of US fertility clinics, and half of those not offering it now plan to do so in the future. This according to a national survey conducted in mid 2009 and reported this week in Fertility and Sterility.

Over two thirds of the 143 centers offering oocyte cryo-preservation will do it electively, as opposed to those that offer it only to women undergoing cancer treatments that threaten their natural fertility.

Go West, but be prepared to pay…

Centers located in the Western part of the US are more likely to offer elective egg freezing than those in the East. Not surprisingly, centers that only accept out of pocket (as opposed to insurance) payments were more likely to offer the procedure, reflecting the history of infertility advancement, which, unlike almost any other area of medicine, has largely been financed by private individual dollars.

Pregnancy Rates – Mother Nature is Still Better

A total of 337 live births from 1,845 cryopreservation cycles were reported, with an overall pregnancy rate of 39%.

Given that 80% of these women would probably be expected get pregnant spontaneously within a year if they had tried to do so naturally, egg freezing is still a far cry from mother nature.  One could argue that egg freezing offers about the same odds of pregnancy a women would have if she delayed natural pregnancy till her early 40’s, begging the question as to whether or not elective egg freezing is worth it for younger women.

There may be an advantage to egg freezing in that younger eggs have less chromosomal abnormalities such as Down’s syndrome than older eggs, and data to date suggest that freezing does not increase chromosomal abnormalities. However, until we have long term developmental outcomes from a large cohort of children born after cryopreserved oocyte cycles, that advantage remains theoretical.

And while these numbers may look good when compared to embryo cryopreserved cycles, which have a reported pregnancy rate of about 21% per thawed cycle, it is important to remember that women undergoing embryo freezing are largely a population with a diagnosis of infertility using IVF, while women electively freezing oocytes would be expected to have normal fertility rates.

Caveat

Only about 60% of clinics participated in the survey, so the actual number of cycles may be higher than reported. Conversely, the actual pregnancy rates could be lower if only centers with good statistics repsponded to the survey.

Slow or fast freeze?

Centers using only slow freezing had marginally higher pregnancy rates than those offering other freeze methods, but this does not control for multiple other factors that can affect a center’s pregnancy rates, including patient age. Because there are so many factors that can impact outcomes, I would not use this measure as a sole reason to include or exclude a center from clinical consideration.  Most good centers are studying this issue closely.

Bottom Line

Oocyte preservation, though increasingly available and promising, remains experimental. Centers conducting the procedure should be doing so under IRB guidance, as recommended by the Association for Reproductive Medicine.