Successful Human Egg Freezing

I helped to established a successful Fertility Preservation (FP) program using a technique known as oocyte cryopreservation (egg freezing). 

Prior to 2004, only a handful of births from thawed, frozen eggs had been reported, but over the last 19 years, the technique has flourished. Today, more than 8,000 healthy babies have been born from oocyte freezing and thawing around the world. Importantly, the incidence of birth defects in these babies does not appear to be increased as compared to natural conceptions (Noyes et al, 2009). Still, the egg freezing techniques are exquisitely precise and have not yet been mastered by all in vitro fertilization (IVF) programs. The technique I use has been able to achieve high pregnancy rates. Under my direction, more than 200 live births have been achieved where women froze and then, subsequently thawed their own (autologous) oocytes. The majority of fertility programs around the world have very few live births using women’s own eggs. Egg freezing is useful for people of reproductive age diagnosed with a malignancy requiring chemotherapy or surgery (or other treatment) that will render them infertile. It can also be used to extend childbearing potential for a variety of other reasons.

Egg quality is best when in reproductive prime, meaning between the ages of 16 and 28. Eggs are usually still of adequate quality in the mid-reproductive years (meaning between the ages 29 and 38) and may remain usable (but definitely with diminished chance for producing pregnancy) in the late-reproductive period (age 39 to 43 years). If necessary or possible, it is ideal to have eggs that are frozen when they are of the best quality possible. For instance, eggs frozen at the age of 35 are superior to fresh eggs produced at 43 years of age. In addition, eggs frozen prior to chemo- or radiation therapy that is known to affect ovarian function is preferable to freezing after these treatments have been started. To my knowledge, the oldest women who has frozen her OWN eggs and then thawed them to achieve pregnancy was 42 years old at the time of freezing.

An oocyte cryopreservation treatment cycles starts the same way as a traditional IVF treatment cycle and involves stimulating the person’s ovaries with a fertility medication called follicle stimulating hormone (FSH). Normally, during the reproductive years, a body releases one egg from the ovary near the middle of each menstrual cycle. The fertility medication stimulates maturation of more than the usual one egg so that multiple oocytes can be obtained from one treatment cycle. Follicle stimulating hormone is administered as a daily subcutaneous injection for about one week, during which time monitoring of the ovarian response is necessary (through blood tests and sonograms). Once the eggs are deemed ready by the doctor, a late-night shot is necessary, followed ~1.5 days later by the oocyte harvest procedure, commonly known as the “egg retrieval”. The harvest is usually performed under mild sedation and takes about 10 minutes to complete. Once removed from the body, the eggs are transferred to the clinical laboratory where they are initially evaluated for health, and then frozen within a few hours. The number of oocytes retrieved varies from person to person and may be anywhere from 0 to 45, depending on age and how the individual”s body responds to the fertility medications.

The average number of eggs retrieved for the purpose of deferring reproduction is about 12, the range being about 2 to 45. To date, medical egg freeze cycles (e.g. those performed for cancer patients) have resulted in an average of 16 eggs retrieved (range 1 – 40) with 12 mature eggs frozen. To my knowledge, on of my patients is the oldest cancer survivor worldwide to achieve live birth from frozen-thawed oocytes; she was 40.5 at the time the eggs were frozen and 43 when the eggs were thawed. Having said that, it’s important to appreciate that not all oocytes are suitable for freezing. It is important to appreciate that usually only about three-quarters of retrieved eggs are mature and only mature eggs are currently frozen for later use. It is also necessary to point out that not all eggs are meant to be babies and not even the healthiest appearing eggs can be guaranteed to create pregnancy. It takes, on average, 8-plus eggs to achieve one chromosomally-competent embryo and the number of eggs needed rises with age at time of freezing. Unfortunately, some thaw cycles result in no viable embryos for transfer or usage.

In 2012, the American Society of Reproductive Medicine (ASRM) lifted the experimental designation for oocyte cryopreservation. I have worked hard to establish a successful oocyte cryopreservation program and am pleased that today, I can offer this treatment option to women.