Egg Freezing

Oocyte cryopreservation, also known as Egg Freezing has recently had a resurgence of interest in the last few years due to its numerous potential benefits.

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Egg freezing can be beneficial for a number of reasons including:

  1. Facilitation and reduction in the cost of oocyte donation.
  2. Provide a mechanism to “maintain” the reproductive potential of women undergoing deleterious therapies (e.g., chemotherapy).
  3. The provision of egg cryostorage for women wishing to delay their reproductive choices.
  4. Women with a family history of early menopause. Some forms of early menopause (premature ovarian failure) are genetically-linked. Egg freezing offers a chance to preserve eggs before they are all depleted.
  5. Legal advantages in regards to custodial issues.
  6. An option for patients who have potential ethical issues with embryo freezing.
La Jolla IVF was featured in several egg freezing articles in both the May 2004 issue of Glamour Magazine and in the San Diego Union Tribune in May 2004. Dr. David Smotrich of La Jolla IVF says, “I am cautiously optimistic regarding the technique of freezing eggs which could potentially allow women to preserve their fertility into the future.”

 

 To date, The American Reproductive Society of Reproductive Medicine still considers egg freezing an experimental procedure as the number of offsprings derived from cryopreserved oocytes has been limited. Even though the first baby produced from a frozen egg was born more than ten years ago, it is not until recently studies have shown improved post-thaw oocyte survival, fertilization and pregnancy rates rivaling those of fresh oocytes. One issue with freezing eggs is that the oocyte is extremely fragile due to its large size, water content and chromosomal arrangement. In the mature oocyte, the metaphase chromosomes are lined up by the “meiotic spindle” along the equatorial plate. It has been well proven that the “meiotic spindle” is easily damaged by intracellular ice formation during the freezing and/or thawing process. In addition, the hardening of the egg shell (zona pellucida) post-thaw adversely affects the normal fertilization process.

As technology has emerged, laboratory findings have linked these recent improved egg survival, fertilization and pregnancy rates to the quality of the egg used as well as modification in cryopreservation and egg freezing fertility techniques. Most leading clinics offering egg freezing, La Jolla IVF included, have moved from the traditional slow-freezing techniques to a Vitrification process due to its superior pregnancy rates and use the fertilization technique of Intracytoplasmic Sperm Injection (a single sperm is passed through the zona pellucida) to overcome the issue of the hardening of the eggs zona pellucida post thaw.

Despite past concerns of increased potential for chromosomal abnormalities in a cryopreserved oocyte, studies have not been able to demonstrate any abnormal or stray chromosomes in thawed oocytes nor any developmental deficits in any of the children born post thawing.