Dr. Chris Herndon
Increasing number of single-women either choose or feel the need to delay childbearing due to professional or personal reasons. For years, the only efficient option available to them for fertility preservation was to freeze embryos after IVF using sperm from an anonymous or known donor. Embryos have been successfully frozen and thawed for three decades. The embryo’s ability to survive the freeze/thaw process depends on its quality, but in general, good-quality embryos survive the process well and are likely to implant.
While the first live birth from frozen-thawed unfertilized egg was reported in 1986, it was over a decade and half before the process became efficient enough for clinical use. The low success rate of freezing eggs was attributable to the delicate protein structures (called spindles) which suspend the chromosomes in a mature egg. The spindles are easily damaged by ice crystals during the freezing process. The safety and success rates for egg-cryopreservation improved only with the development of vitrification – a rapid cooling technique that minimizes formation of ice crystals, leaving the eggs suspended in a glass-like state.
Egg within a mature follicle
An egg within a mature follicle
As of October 2012, oocyte cryopreservation is no longer considered experimental by the American Society of Reproductive Medicine (ASRM). However, it is important for patients to realize that no single clinic has achieved a large number of live births from frozen-thawed eggs. To date, approximately 1000 live births have been reported worldwide. For comparison, hundreds of thousands if not millions of healthy children have been born from frozen-thawed embryos and sperm. Current studies indicate that conceptions resulting from egg-freezing are safe with no reported increase in congenital or chromosomal anomalies.
What is the chance of a child resulting from a single cycle of egg-banking?
The answer requires thorough individualized assessment focusing on the woman’s age and ovarian reserve. It is clear that egg banking does not guarantee a baby. Even with IVF and embryo banking, a better established approach to fertility preservation, success rates per cycle generally do not exceed 50% in the best prognosis groups.
Oocyte freezing is a complex and expensive treatment, although its cost is slightly less than that of an IVF cycle. The development of safe and efficient egg-freezing is an important option for women seeking preservation of their fertility for family building in the future. Prospective patients are encouraged to set up an appointment for individualized assessment and counseling.
