Women, particularly single women, who delay childbearing due to personal circumstances now have the option of freezing their own eggs so that these may be fertilized and implanted at a later date. This significant step forward in fertility treatment enables women to take advantage of their body’s fertility at a time when eggs are at their healthiest.
Women have on average about 600,000 eggs at birth, and this supply diminishes at a rate of about 1,000 per month, right from
the day she is born. This decline is part of the natural aging process, and is commonly referred to as a woman’s biological
clock. The loss of oocytes from the ovaries is relentless and continues even in the absence of menstrual cycles, and even
when women are pregnant, nursing or taking oral contraceptives. The rate at which eggs are lost is also thought to accelerate
during the late 30’s and early 40’s so that women generally lose the natural ability to have children around their mid 40’s.
Importantly, egg quality also diminishes with time,
with miscarriages and chromosome defects becoming more common with later age at pregnancy.
Previously, a woman not ready for parenthood and wishing to use her own eggs had the option of harvesting her own eggs through IVF and then fertilizing these eggs with partner or, in the case of women that do not have a partner, anonymous donor sperm.
The resulting embryos would then be frozen and implanted at the appropriate time.
Embryo freezing, as well as third party parenting options such as egg donation or adoption still are viable and attractive options for many older would-be parents. For younger women who know in advance that they may want to extend their fertility potential, egg or oocyte freezing (also called fertility preservation) provides the ability to preserve a woman’s own genetic material until such time as she is ready to pursue parenthood.
Xenith Advance Fertility Centre has been freezing eggs since 2007 when we first embarked on a project freezing donor eggs. Since then, we have performed many cases of egg freezing and the number of patients coming in for oocyte freezing is steadily rising. While once considered an experimental procedure, success with egg freezing has led to widespread acceptance. It is now being performed in IVF centres around the world.
When talking with interested patients, we do recommend that women carefully consider this option before embarking on it. For instance, some women may meet a subsequent partner and never use their banked eggs, while some may rely on these banked eggs for a future pregnancy but their particular eggs might not result in a viable pregnancy. Unfortunately, there is no way to guarantee or know what the outcomes will be at the time of thawing the eggs. We suggest a detailed discussion about fertility preservation with your PFC physician before choosing this option.
The egg freezing process begins with In Vitro Fertilization (IVF) so that multiple eggs may be produced for freezing. A high number of eggs provide ample opportunities for fertilization and pregnancy later on.
Women interested in freezing their own eggs will first be asked to undergo a series of fertility tests to assess their reproductive potential and readiness for the IVF process.
Initial evaluation of ovarian reserve. The first step for those wishing to freeze their own eggs is a consultation with one of PFC’s reproductive endocrinologists. One of the major considerations in fertility preservation is the age of the woman. Is the patient still young enough at the time of freezing that they have a high likelihood of future success using these eggs? How many eggs might be needed to help ensure future success? Ingeneral, the older the patient at the time of egg freezing, the lower the rate of future success. This is true for all IVF patients, and not just for those freezing oocytes, because oocyte quality diminishes with maternal age. Therefore, for older women we might suggest more than one cycle with oocyte freezing to increase the number of eggs banked and theoretically, the odds
of future success.
Your doctor will also conduct a number of tests to determine your potential for creating a high number of eggs for freezing.
FSH (follicle stimulating hormone) and Estradiol and AMH Blood Testing (indirect measure of ovarian reserve). As part of the body’s normal reproductive cycle, a hormone called FSH recruits eggs to grow in the ovaries. High FSH levels in a woman indicate that the body is working extra hard to grow eggs, which can in turn be an indication of low egg numbers in the ovaries. This is called diminished ovarian reserve or DOR. A lower (or normal) FSH value indicates a greater potential for creating a substantial number of eggs for freezing.
Women having their FSH levels checked must have it done on day 2 or 3 of the menstrual cycle when the eggs are being recruited. Estradiol is also measured at the same time as a means of making sure that the FSH level is truly indicative of ovarian reserve. Estradiol comes from the granulosa cells surrounding the growing oocytes and this hormone actually suppresses FSH once oocyte growth has started. So if FSH is measured say on day 3 and Estradiol is already at a high level, the FSH value will have started to drop and will not be an accurate measure of ovarian reserve. A lower estradiol value suggests that oocyte growth has not yet started and we would therefore expect FSH to be at its highest level. The highest level for a given patient is what the test aims to measure, and measuring estradiol at the same time makes sure that we get that number.
Antral Follicle Count (AFC) and Anti-Mullerian Hormone (AMH) (direct measure of ovarian reserve). Oocytes grow inside follicles, and the small developing follicles that exist in the ovary are called antral follicles. An antral follicle consists of an egg, several layers of estrogen producing granulosa cells that surround the egg, and a small pocket of fluid (or cyst, called a follicle). Antral follicles in the female ovary viewed with an ultrasound scan can indicate a woman’s potential to produce multiple eggs for freezing. The higher the antral count (AFC), the higher a woman’s potential to produce an adequate number of eggs to be harvested and frozen.
Anti-Mullerian Hormone (AMH), is a hormone produced by the ovarian follicles. Measurement of AMH hormone levels likewise serves to assess ovarian reserve. A higher AMH count indicates higher ovarian reserve and thus greater fertility potential. Because it is not dependent on where a woman is in her cycle, it can be an easier test to obtain and interpret.
Our treatment protocol involves the preparation of your ovaries for the production of the mature eggs needed for the freezing process. Full details of this process will be provided at the time of your formal entry into the program, but a summary of the process is provided here for your reference and understanding:
Involves waiting for your normal menstrual period to begin. Depending upon the treatment protocol prescribed for you, with the beginning of your menses, you will either be given instructions to begin your fertility drugs, or instructions to wait for a certain date within the three weeks following the start of your period to begin a medication to allow the Doctors the opportunity to optimize your ovaries for the fertility drugs that will follow.
Involves the administration of fertility medications designed to allow your ovaries to begin the growth of the several eggs that will be removed for subsequent freezing. During this phase, you will be self-administering daily fertility injections to allow for the successful production of multiple healthy eggs. You will be shown how to take these injectable medications prior to using them. While taking these medications, you will need to be seen for painless ultrasound studies and blood tests 3-4 times over the 10-12 day period these medicines are being used. These studies may be carried out near your home, or at any of our offices.
After your eggs have been determined to have matured adequately, you will be scheduled for the surgical harvesting of your eggs. This is done by the Doctor at our facilities. In nearly all instances, the procedure is carried out with a light sedative and pain medication that allows for a very rapid recovery. You will be discharged from the office when it has been determined that you are stable, usually within 1-3 hours of your procedure.
After your eggs have been recovered, they are prepared in our cryopreservation laboratory by the embryologist and who will
assure the healthy appearance of the eggs and begin the process of preparing the eggs for freezing. We use the most advanced "vitrification" (snap freezing) techniques for egg freezing that are providing success rates far superior to earlier "slow freezing" methods. The freezing process rapidly lowers the temperature of human eggs to a point where all metabolic processes (aging) is halted.
Following the freezing process, your eggs will be transferred to a liquid nitrogen storage chamber where they are able to be effectively stored in the frozen state. The initial, short term storage of your eggs will occur at our facility, however long term storage will be required at a special "cryobank" which is a facility where long term secure maintenance of frozen human specimens occurs. You will be given information concerning a contract that you will need to enter into providing for the long-term storage of your eggs.
When the time arrives for you to use your cryopreserved eggs, you will need to make arrangements with our facility at least 3 months in advance of the time you desire the eggs to be thawed and fertilized. It must be remembered that the eggs have been frozen UNFERTILIZED, and that the fertilization of previously frozen eggs requires special techniques and handling. The successful fertilization of cryopreserved eggs is greatly enhanced by the use of a process called "ICSI" (intrascreeningcytoplasmic sperm injection). Utilizing this method assures the best chance for the fertilization of the eggs and their subsequent development into healthy embryos with the potential to produce an ongoing pregnancy. When we are contacted by you with a request for use of the frozen eggs, we will begin making the arrangements for the treatment cycle required to assure the best chance for a successful pregnancy outcome for you.
Thawing. When the patient decides they are ready to use their eggs, they will be thawed in the laboratory. The thawing is a rapid procedure performed on the day the eggs will be fertilized and must be synchronized with a woman’s cycle. Over 90% of frozen eggs, on average, survive the freeze-thaw process.
Fertilization. Thawed eggs are next fertilized in our laboratory using a procedure called Intra-Cytoplasmic Sperm Injection (ICSI) in which a single sperm is injected into each egg. Because the protein coat surrounding a frozen-thawed egg is hardened by the freezing process, ICSI rather than conventional mixing of eggs and sperm is required for successful fertilization. On average, about 70% of the injected eggs will be expected to fertilize normally.
Embryo culture. Once the eggs have been fertilized, they will remain in the laboratory for 3 to 5 days, growing and dividing, now called embryos. Not all fertilized eggs will divide to make nice embryos. The number that do survive and progress is again related to a woman’s age, as embryos have very abnormal chromosome numbers will tend to arrest their development within the first few days.
Embryo transfer. Prior to transfer, our doctor will discuss with you the number of embryos recommended for transfer. This number is based on a number of factors. The number we recommend transferring will be made primarily based on the age of the egg provider at
the time the eggs were frozen. For example, if the woman was 28 when eggs were frozen, a doctor might recommend only 1 embryo, but if she was 37, we would be likely to recommend 2 embryos. It is important to remember that it is your age at the time that the eggs were frozen is what matters, and not your age when you return to use these eggs. Your doctor will transfer the fertilized eggs (embryos) into the uterus using a small insertion catheter and under visualization with an abdominal ultrasound. The transfer feels similar to a Pap smear and does not require anesthesiaThe procedure takes about 15 minutes (the transfer itself takes just 30 seconds).
Re-freezing of excess embryos. According to the decision one makes with their physician, excess embryos may be re-frozen. Re-freezing the fertilized eggs (embryos) is safe and will make it possible to do another transfer if the first one does not work, or to have a future child if the first transfer does work.
We invite you to schedule a fertility preservation consultation with the San Francisco Bay Area’s 'Top Docs' at Xenith Advance Fertility Centre ®. We recommend that patients gather questions for the consultation beforehand, to make most of your appointment time.
Some common questions include:
Xenith Advance Fertility Centre is conveniently located in the San Francisco Bay Area, near many local Northern California communities.