Oocyte Cryopreservation
Bay IVF - Advanced Reproductive Care                                Palo Alto  650-322-0500


Egg Freezing: Preserving Your Fertility

Stop the clock on aging of your eggs!


Impact of Female Age
Female fertility begins to decline many years prior to menopause despite continued regular ovulations. The likelihood of a successful pregnancy decreases by approximately 10% to 15% each year after the age of 32 and at an even faster rate after the age of 37. Most women 42 and older will require Donor Egg In Vitro Fertilization to have a child.

If you plan to delay starting your family, or if you have a medical condition that will require radiation or chemotherapy, you may decide to have your eggs retrieved from your ovaries, vitrify (cryopreserve) them, and store them for your future use.

Vitrified eggs (oocytes) are kept in liquid nitrogen storage. They remain in a suspended state, “frozen in time”. The uterus also does not “grow old”, so the probability of a successful outcome from cryopreserved eggs is independent of the patient´s age at the time the eggs are thawed, fertilized, and transferred inside the uterus.

You may also wish to consider Embryo Banking as an alternative to the Egg Freezing treatment. The advantage of freezing embryos (Embryo Banking), as opposed to freezing unfertilized eggs, is a more predictable survival of the frozen-thawed embryos. Additionally, it provides a higher probability of a successful outcome for women 35 years or older at the time of embryo freezing. Embryo Banking will require fertilization of eggs with your partner's sperm or sperm from a sperm bank prior to freezing. Some patients decide to combine the Egg Freezing and Embryo Banking procedures into a single treatment.

Treatment Logistics
The Egg Freezing treatment first requires maturing multiple eggs within the ovaries. This process is similar to the process of obtaining multiple eggs in In Vitro Fertilization.

The eggs are then retrieved from the ovaries, cryopreserved, and stored at our clinic for your future use.

We use gentle, individualized ovarian stimulation protocols and strive for the highest egg quality. This approach decreases the likelihood of ovarian hyperstimulation without reducing the probability of a successful outcome.

Most patients will be able to continue their everyday lifestyles during their treatment. It is our goal to make your treatment experience pleasant, relaxed, and as natural as possible.

Probability of Success
The probability of fertilization and pregnancy from frozen-thawed fertilized eggs is similar to In Vitro Fertilization pregnancy probability with fresh (unfrozen) eggs when vitrified oocytes come from young women (35 years and younger). Unfortunately, the success rates with egg freezing appear to decline significantly for older women (38 years or older).

No increase in chromosomal abnormalities, birth defects, or developmental deficits has been noted in the children born from cryopreserved oocytes.


Egg Freezing Procedure


Egg Freezing Procedure


Oocyte Cryopreservation consists of:

  1. Ovarian stimulation
  2. Egg retrieval procedure
  3. Cryopreservation (vitrification) of oocytes
  4. Oocyte storage


  1. Ovarian Stimulation

    There are several different forms of ovarian stimulation protocols, each with many modifications. Your treatment is always individualized to maximize the probability of a successful outcome. The selection of an optimal protocol for your Egg Freezing is based on your reproductive history and your pre-treatment evaluation. Below are three examples of Egg Freezing treatment protocols used at Bay IVF Clinic. Your individualized protocol may take less or more time to complete.

Ovarian Stimulation Example #1


Ovarian Stimulation Example #1


Ovarian Stimulation Example #2


Ovarian Stimulation Example #2


Ovarian Stimulation Example #3


Ovarian Stimulation Example #3


Follicle stimulating hormone (FSH) or a combination of FSH/luteinizing hormone (LH) hormones will stimulate the production of multiple eggs in the ovaries. They are given once a day or once every other day subcutaneously with tiny needles for approximately ten days.

During this time, your progress is monitored by estradiol (estrogen, E2) and progesterone blood levels and ultrasound examinations.

Ovarian stimulation should result in the development of several eggs in each ovary. The ultrasound image below shows a stimulated ovary. Each of the several follicles (dark circles) contains a microscopic egg.


Ovarian Follicles


  1. Egg Retrieval Procedure

    The egg retrieval procedure is performed at our Center. The procedure only takes a few minutes, and we use very comfortable conscious sedation for analgesia.

    Since 1985, we have done many thousands of egg retrievals and are very experienced in retrieving eggs from the ovaries.

    Under ultrasound guidance, the tip of a thin needle is passed through the top of the vagina into the cul-de-sac (behind the uterus). The ovaries are located near the bottom of the cul-de-sac allowing the tip of the aspirating needle to enter the ovarian follicles and aspirate the follicular fluid from them. The fluid is examined under a microscope to identify the eggs.

  2. Cryopreservation of Oocytes

    On average, eight to fourteen eggs are aspirated during the egg retrieval procedure. The eggs are identified under the microscope and placed in petri dishes filled with culture medium. The composition of the culture medium resembles the fluid secreted by the Fallopian tubes.

    Six hours after the egg retrieval, the eggs are cryopreserved (vitrified). Preparation for the freezing process involves removing water from within the eggs and replacing it with cryo-protective substance to prevent ice crystal formation during vitrification and subsequent thawing. The eggs are then flashed cooled to −196 °C (−321 °F). Such rapid freezing (vitrification) prevents damaging water crystal formation.


    Frozen Oocyte Storage


  3. Oocytes Storage

    Following the vitrification process, the eggs are transferred to a liquid nitrogen storage chamber in our Center. Theoretically, there is no limit on the length of storage, but conceiving past the age of 40 may result in a high risk pregnancy.


When you decide to conceive with your cryopreserved eggs, you will typically have one or more eggs thawed, fertilized, and transferred inside your uterus. The implantation rate of the thawed fertilized eggs (embryos) is similar to the un-frozen egg embryo implantation rate, and, as mentioned above, is primarily dependent on the patient’s age at the time of egg freezing.


Please use the following links for financial information about Egg Freezing and to schedule a consultation.


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