While significant enhancements in technology have brought about much improved success rates following freezing (cryopreservation) of embryos, results following egg freezing have been very disappointing. This is the reason why, since the first pregnancy from frozen eggs was reported by Chen in 1986, only about 1000 frozen-egg births have been documented worldwide.

Yet, hardly a month goes by where we do not hear or read about the great benefits associated with egg banking and how by freezing their eggs, women could confidently exercise control over their reproductive performance.  But presently such claims belie reality.

It is not uncommon to see advertisements of a 30-40% birth rate per transfer procedure  using embryos derived from previously frozen eggs… But this statistic is “empty” because it does not tell the whole story.  It fails to address the fact that in the final analysis each egg being frozen and banked will have no more than a 4% chance that it will survive the thaw, be successfully fertilized, and upon being transferred to a recipient uterus,  result in a live birth.  It also does not show that because (even in young women) two out of three eggs are chromosomally abnormal (aneuploid) and “incompetent.” That is, they are incapable of propagating a normal pregnancy.  Additionally, the incidence of aneuploidy increases progressively with advancing age.  Because of this fact, we can infer that the vast majority of eggs being frozen/banked are “incompetent”. This is why most Egg Banks require a commitment on the part of patients to bank least 15-20 eggs before stopping.  It should come as no surprise that our governing body, the American Society for Reproductive Medicine (ASRM), currently regards egg freezing/banking as an experimental procedure.

But there is good news on the horizon for those wishing to freeze their eggs. The relatively recent introduction of an ultra-rapid egg freezing method (vitrification) and the introduction of a reliable genetic test (CGH) is changing all this.

1. Egg Vitrification: Unlike conventional (slow) freezing which damages eggs by causing ice crystals to form in them, ultra-rapid vitrification avoids the formation of intracellular ice crystallization,, reduces egg damage and thereby markedly improves egg freeze-thaw survival, subsequent fertilization potential and ongoing pregnancy rates.
2. CGH Genetic testing allows us to selectively bank chromosomally normal eggs:  In 2007 we were the first to report (RBM-online) on a study where, using metaphase CGH, we were able to identify, vitrify and bank only chromosomally normal eggs. We reported that upon thawing (warming) such pre-vitrified eggs,  90% survived, and that upon fertilizing such eggs through ICSI and then transferring  up to two (2) advanced embryos (blastocysts) to the uteri of designated recipients, the baby rate was >60% per ET.  AND what is more, the baby rate per frozen egg was many fold higher (27% versus 4%) than had ever previously been reported. More than 30 babies have been born to date using this approach.

So…. while pregnancy rates following egg freezing are profoundly affected by the freezing process, it is the process of identifying and freezing/banking ONLY “competent” (CGH-normal) eggs that represents the real breakthrough. It will be the integration of these two components that ultimately will:

• Enable women in the reproductive age to safely postpone having babies, without fear that the inevitable decline in egg quality which accompanies aging will deny them having a family they are ready. We refer to this as “Fertility Preservation.”
•  Benefit women with existing medical conditions (such as breast cancer, leukemia, lymphoma etc.) which preclude initiation of pregnancy until cured.  In such cases, treatment (e.g. by radiotherapy or chemotherapy) would otherwise often render these women permanently infertile. The successful cryopreservation and storage of their eggs could avoid denying such women the opportunity of parenthood with their own eggs. We call this Fertility Rescue.
• Lead to genetically competent donor eggs being banked for subsequent purchase (at a comparatively low cost) by women with failing or failed ovaries who wish to have babies.