Fertility cryopreservation at a glance
- Fertility cryopreservation, also referred to as fertility preservation, is the freezing and storing of mature eggs (oocytes), fertilized eggs (embryos) or sperm for later use in fertility treatments to achieve pregnancy.
- Fertility preservation assists those who wish to save eggs before age diminishes their quantity and quality to increase the chance of a future pregnancy with in vitro fertilization (IVF).
- Fertility cryopreservation can be an option for people who may want to become parents later in life but are just not ready yet for various reasons, such as career goals or not having met a partner.
- Oncofertility is fertility preservation for patients facing cancer treatments or other medical conditions that may impact their future fertility.
- We recommend transgender patients who are transitioning also consider fertility preservation.
- Some patients who are undergoing IVF use cryopreservation to preserve their unused embryos for use in future IVF treatments.
- When their family is complete, some patients choose to donate their extra frozen embryos to others needing viable embryos, a service we offer.
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What is fertility cryopreservation?
Cryopreservation is a method of freezing cells and tissues by cooling them to very low temperatures and storing them for future use.
Fertility cryopreservation involves the freezing and storage of mature eggs, sperm, embryos, ovarian tissue or testicular tissue for later use in assisted reproductive treatments.
Freezing stops all biologic activity and preserves existing cells’ viability. Ongoing advances in fertility preservation have improved the process and success rates, resulting in an increase in its use. In 2012 the American Society for Reproductive Medicine (ASRM) determined that egg freezing should be included as a standard clinical practice for fertility preservation and should no longer be considered experimental.
Freezing eggs and embryos has enabled many people, such as heterosexual partners, single mothers and LGBTQIA couples and individuals, to become parents who would otherwise not have that chance.
Because sperm isn’t as fragile as eggs or embryos to freeze, sperm freezing has been a viable fertility treatment option for over 40 years.
Fertility cryopreservation is an option for those who:
- Wish to have children in the future but who are not currently ready due to career, relationship or other factors
- Will be undergoing treatment for cancer or other serious diseases that could affect their fertility
- Are an LGBTQIA individual or couple and require frozen eggs, embryos or sperm for family building
- Have extra viable embryos remaining after an in vitro fertilization (IVF) cycle that they hope to use to attempt another pregnancy in the future
Fertility cryopreservation using vitrification
The preferred method of freezing embryos and eggs is called vitrification, a flash-freezing method in which the cells are first bathed in cryoprotectant and rapidly cooled to -320 degrees Fahrenheit in liquid nitrogen.
Compared with older methods of freezing, vitrification results in the lowest occurrence of ice crystal formation, which happened in older methods that damaged cells by causing them to tear or rupture.
The process of freezing suspends all biological activity until the cells are thawed for use in the future. It requires great skill to appropriately vitrify eggs and embryos, which can involve adjustments for the individual specimen. Equally as important for success is the process of safely thawing them, which is dictated by the way they were frozen (vitrified) initially.
Meet our lab team
Fertility Specialists Medical Group has an experienced team of embryologists and state-of-the-art lab facilities to freeze eggs, embryos and sperm.We work with a third-party resource if sperm freezing is for donation or for oncofertility. Frozen eggs, embryos or sperm can be stored at our fertility clinic if the intention is for relatively short-term use. As we are not a long-term storage facility, we provide options for shipping to such a facility if patients do not plan to use their tissues in the immediate future.
Freezing eggs to preserve fertility
Egg freezing, also known as mature oocyte (egg) cryopreservation, is the freezing and storage of unfertilized eggs.
Egg freezing is an option that can make it possible to become pregnant using a patient’s own eggs in the future by taking advantage of the quantity and quality of the eggs available when a woman is younger.
Egg freezing may be beneficial for those:
- Who wish to advance their careers before starting a family
- With jobs that are hazardous in a way that can harm their eggs
- Who prefer to delay parenthood for relationship reasons
- Who are part of an LGBTQIA couple or an individual requiring donated eggs to have a child
- Who are transgender and transitioning
- Who will undergo cancer or other medical treatments that could lead to infertility
Egg freezing is also used for egg donation when the fresh oocytes (eggs) are collected from the donor.
The egg freezing process
During an egg freezing cycle, a patient will go through many of the same steps that are involved in a typical IVF cycle: ovulation stimulation, ultrasound monitoring and egg retrieval. After egg retrieval, the eggs are typically frozen within an hour.
To prepare the patient for this process, we prescribe synthetic hormones in order to stimulate egg production. This causes more eggs to develop to maturity than during a normal menstrual cycle. After the eggs have matured, we prescribe an ovulation inducing medication and all viable eggs are collected.
Using frozen eggs
When the person whose eggs were frozen or someone using donated frozen eggs is ready to begin fertility treatment, the embryologist will thaw the frozen eggs in preparation for fertilization with sperm.
Typically, the embryologist will use a technique called intracytoplasmic sperm injection (ICSI), injecting one sperm directly into the cytoplasm of the egg, to optimize outcomes.
Eggs that have fertilized, which are called embryos, are then cultured in incubators for five days. Those embryos that appear to have developed appropriately can then be transferred into the uterus, biopsied for further testing, or frozen for future use.
Frozen embryos for future fertility
Embryo cryopreservation is a technique we recommend for fertility preservation to address the different needs of patients, including those below.
- When more viable embryos are produced than are used in a single IVF treatment cycle, transfer of a single embryo is generally recommended
- To provide another chance for pregnancy if the first IVF attempt fails, keeping the couple or individual from having to go through egg retrieval and embryo development again
- Preserving embryos before a woman’s upcoming cancer of other medical treatment that may damage fertility
- To donate extra embryos to others in need
With current technology, embryos generally have a greater thaw survival rate than eggs, and thus have a greater chance of resulting in a pregnancy in the future. Patients undergo a typical IVF cycle to create embryos.
Our embryologists culture embryos to the blastocyst stage (day 5, 6 or 7 after retrieval), and those embryos that meet quality criteria by microscopic evaluation are frozen. At this stage, we may recommend preimplantation genetic testing to identify embryos that have a normal number of chromosomes.
Embryos with an abnormal copy number of chromosomes result in either failed implantation, miscarriage or babies born with chromosomal abnormalities (like Down syndrome). By identifying embryos that have a normal copy number, we can increase pregnancy rates and reduce miscarriage rates, as we have more information on which embryo to transfer.
The embryos remain frozen until the patient is ready to use them. Patients can also give extra frozen embryos to others through our embryo donation program.
Interested in donating your embryos to others?
Because sperm has a lower water content (about 50%) than an egg, sperm tends to be less susceptible to damage from ice crystal formation during the freezing process.
A study in the journal Human Reproduction indicates that slow freezing is still the most common method of sperm cryopreservation, though vitrification of sperm is advancing.
How long frozen sperm remains viable isn’t known, but 40-year-old frozen sperm has resulted in a successful pregnancy. Male fertility declines somewhat with age, though not as markedly as does female fertility, so some patients choose to freeze their sperm to use later.
For short-term storage (use in an upcoming treatment cycle), sperm can be frozen at FSMG. In cases of freezing for future use, as a known sperm donor or for oncofertility, FSMG doesn’t offer on-site sperm freezing. We work with a reliable third-party resource for sperm freezing, necessary testing and storage.
Fertility preservation for cancer patients and others
Patients who are undergoing cancer therapies that can affect fertility may desire to preserve sperm, eggs or embryos prior to treatments. This is also known as oncofertility.
FSMG will work with the patient’s oncologist to develop an oncofertility preservation plan that optimizes future family building goals but also minimizes delays in treatment.
FSMG offers reduced fees for both female and male oncofertility preservation when patients face potential loss of fertility due to cancer treatments. We also have relationships with pharmaceutical companies to help minimize medication costs associated with fertility preservation treatments.
Patients about to undergo treatment for an autoimmune disease like lupus, or those with a genetic disease that may impact future fertility, can also benefit from fertility preservation.
Fertility cryopreservation risks and concerns
The main risk associated with cryopreservation is linked to the freezing process and the possibility of damage to frozen eggs and embryos during thaw.
Also of concern is the limited data available on the possible impact of long-term cryopreservation on egg quality. This continues to be an active area of study. For egg retrieval prior to cryopreservation, the patient receives hormones to stimulate the ovaries.
A rare complication of this process is ovarian hyperstimulation syndrome (OHSS), when a patient has a heightened response to the medication. Fortunately, with modern medication protocols, far less than 5% of all IVF patients will experience OHSS.