Egg and Embryo Freezing
Introduction:
Egg freezing can benefit women, particularly those who may face infertility for medical reasons, such as chemotherapy treatment and women wish to freeze their eggs for social reason as well delaying mother hood until later in life.
Sometimes freezing eggs or sperm is part of fertility treatment. Others who don't have fertility problems may also choose to freeze. In some cases treatments can affect fertility; people may be able to freeze eggs or sperms before they have treatment.
The Process Of Egg Freezing:
The process of egg-freezing, or in medical speak, oocyte cryopreservation, involves stimulating the ovaries with hormones to produce multiple eggs, retrieving the eggs from the ovaries and taking them to the lab, where they're cooled to subzero temperatures to be thawed at a later date.
It takes approximately 3 weeks to complete the egg freezing cycle and is consistent with the initial stages of the IVF Process including: 1-2 weeks of birth control pills to temporarily turn off natural hormones. Egg freezing, also known as mature oocyte cryopreservation, is a method used to save women's ability to get pregnant in the future.
Eggs harvested from your ovaries are frozen unfertilized and stored for later use. A frozen egg can be thawed, combined with sperm in a lab and implanted in your uterus (in vitro fertilization). Egg freezing might be an option if you're not ready to become pregnant now but want to try to make sure you can get pregnant later.
Unlike with fertilized egg freezing (embryo cryopreservation), egg freezing doesn't require sperm because the eggs aren't fertilized before they're frozen. Just as with embryo freezing, however, you'll need to use fertility drugs to make you ovulate so that you'll produce multiple eggs for retrieval.
Why It's Done:
Egg freezing might be an option if you're not ready to become pregnant now but want to try to make sure you can get pregnant later.
Unlike with fertilized egg freezing (embryo cryopreservation), egg freezing doesn't require sperm because the eggs aren't fertilized before they're frozen. Just as with embryo freezing, however, you'll need to use fertility drugs to make you ovulate so that you'll produce multiple eggs for retrieval.
You Might Consider Egg Freezing If:
You have a condition or circumstance that can affect your fertility: These might include sickle cell anemia, autoimmune diseases such as lupus, and gender diversity, such as being transgender.
You need treatment for cancer or another illness that can affect your ability to get pregnant: Certain medical treatments - such as radiation or chemotherapy - can harm your fertility. Egg freezing before treatment might enable you to have biological children later.
You're undergoing in vitro fertilization: When undergoing in vitro fertilization, some people prefer egg freezing to embryo freezing for religious or ethical reasons.
You wish to preserve younger eggs now for future use: Freezing eggs at a younger age might help you get pregnant when you're ready.
You can use your frozen eggs to try to conceive a child with sperm from a partner.
Risks:
Egg freezing carries various risks, including:
Conditions Related To The Use Of Fertility Drugs: Rarely, use of injectable fertility drugs, such as synthetic follicle-stimulating hormone or luteinizing hormone to induce ovulation, can cause your ovaries to become swollen and painful soon after ovulation or egg retrieval (ovarian hyperstimulation syndrome). Signs and symptoms include abdominal pain, bloating, nausea, vomiting and diarrhea. Even rarer is the possibility of developing a more severe form of the syndrome that can be life-threatening.
Egg Retrieval Procedure Complications: Rarely, use of an aspirating needle to retrieve eggs causes bleeding, infection or damage to the bowel, bladder or a blood vessel.
Emotional Risks: Egg freezing can provide hope for a future pregnancy, but there's no guarantee of success.
If you use your frozen eggs to have a child, the risk of miscarriage will be primarily based on your age at the time your eggs were frozen. Older women have higher miscarriage rates, mainly due to having older eggs. Research to date hasn't shown an increase in the risk of birth defects for babies born as a result of egg freezing. However, more research is needed on the safety of egg freezing.
How You Prepare:
If you're considering freezing your eggs, look for a fertility clinic with expertise in the field. Experts are commonly known as reproductive endocrinologists. If the expense of egg freezing concerns you, ask for information about the costs associated with each step of the procedure and the annual storage fees.
Before beginning the egg-freezing process, you'll likely have some screening blood tests, including:
Ovarian Reserve Testing: To determine the quantity and quality of your eggs, your doctor might test the concentration of follicle-stimulating hormone and estradiol in your blood on day three of your menstrual cycle. Results can help predict how your ovaries will respond to fertility medication. Another blood test and an ultrasound of the ovaries might be used to get a more complete picture of ovarian function.
Infectious disease screening: You'll be screened for certain infectious diseases, such as HIV and hepatitis B and C.
Ovarian Stimulation:
You'll take synthetic hormones to stimulate your ovaries to produce multiple eggs rather than the single egg that typically develops monthly. Medications that might be needed include:
Medications For Ovarian Stimulation: You might inject medication such as follitropin alfa or beta (Follistim AQ, Gonal-f) or menotropins (Menopur).
Medications To Prevent Premature Ovulation: Your doctor might prescribe an injectable gonadotropin-releasing hormone agonist such as leu proline acetate (Lupron) or a gonadotropin-releasing hormone antagonist such as cetrorelix (Cetrotide).
During treatment, your doctor will monitor you. You'll have blood tests to measure your response to ovarian-stimulation medications. Estrogen levels typically increase as follicles develop, and progesterone levels remain low until after ovulation.
Follow-up visits will also include having vaginal ultrasound. It is a procedure that uses sound waves to create an image of the inside of your ovaries. It is done to monitor the development of fluid-filled sacs where eggs mature (follicles).
When the follicles are ready for egg retrieval, generally after 10 to 14 days, an injection of human chorionic gonadotropin (Pregnyl, Ovidrel) or another medication can help the eggs mature.
Egg Retrieval:
Egg retrieval is done under sedation, typically in your doctor's office or a clinic. A common approach is transvaginal ultrasound aspiration, during which an ultrasound probe is inserted into your vagina to identify the follicles.
A needle is then guided through the vagina and into a follicle. A suction device connected to the needle is used to remove the egg from the follicle. Multiple eggs can be removed, and studies show that the more eggs retrieved up to 15 per cycle the better the chances of birth.
After egg retrieval, you might have cramping. Feelings of fullness or pressure might continue for weeks because your ovaries remain enlarged.
Freezing:
Shortly after your unfertilized eggs are harvested, they're cooled to subzero temperatures to preserve them for future use. The makeup of an unfertilized egg makes it a bit more difficult to freeze and lead to a successful pregnancy than does the makeup of a fertilized egg (embryo).
The process most commonly used for egg freezing is called Vitrification. High concentrations of substances that help prevent ice crystals from forming during the freezing process (cryoprotectants) are used with rapid cooling.
After The Procedure:
Typically, you can resume normal activities within a week of egg retrieval. Avoid unprotected sex to prevent an unintended pregnancy.
Contact your health care provider if you have:
A fever higher than 101.5 F (38.6 C)
Severe abdominal pain
Weight gain of more than 2 pounds (0.9 kilograms) in 24 hours
Heavy vaginal bleeding i.e. filling more than two pads an hour
Difficulty urinating
Results
Intracytoplasmic sperm injection (ICSI):
When you want to use your frozen eggs, they'll be thawed, fertilized with sperm in a lab, and implanted in your or a gestational carrier's uterus.
Your health care team might recommend using a fertilization technique called intracytoplasmic sperm injection (ICSI). In ICSI, a single healthy sperm is injected directly into each mature egg.
The chances of becoming pregnant after implantation are roughly 30 to 60 percent, depending on your age at the time of egg freezing. The older you are at the time of egg freezing, the lower the likelihood that you'll have a live birth in the future.
Embryo Freezing:
It is the process of freezing one or more embryos to save for future use. Embryo freezing involves in vitro fertilization, a procedure in which eggs are removed from a woman’s ovary and combined with sperm in the laboratory to form embryos. The embryos are frozen and can later be thawed and placed in a woman’s uterus. Embryo freezing is a type of fertility preservation. It may be useful for women with cancer who want to have children after having radiation therapy, chemotherapy, or certain types of surgery, which can cause infertility. Also called embryo banking and embryo cryopreservation.
How Long Can Embryos Be Frozen And Still Be Viable?
As far as medical experts know, frozen embryos remain viable indefinitely. To date, the longest an embryo has been frozen before a successful transfer is 24 years.
Predicted Percent
# of eggs frozen Projected # of embryos Chance of Pregnancy
5 to 10 1 to 2 40%
11 to 15 2 to 4 50%
16 to 20 3 to 6 60%
21 to 30 4 to 8 65%
Embryo Freezing: What You Need To Know:
Successful fertilization may lead to at least one healthy embryo. A doctor can then transfer the embryo to the womb, or uterus. If the treatment is successful, the embryo will develop.
Fertilization often results in more than one embryo, and the doctor can freeze and preserve the remaining embryos. According to an article published in the journal Human Reproduction, the medical community uses the term embryo from the moment that cells divide after fertilization until the eighth week of pregnancy.
Before freezing can take place, people need to create suitable embryos. To do so in the laboratory, doctors must harvest and fertilize some eggs.
First, the person will take hormones to make sure that ovulation happens on schedule. They will then take fertility medications to increase the number of eggs that they produce.
In the hospital, a doctor will extract the eggs, using an ultrasound machine to ensure accuracy.
A person may wish to freeze their eggs. Or, they may wish to use them at once to become pregnant. In this case, the doctor may recommend in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). During IVF, the doctor exposes the eggs to sperm and leaves them in a laboratory for fertilization to take place. After this, the correct term for a fertilized egg is an embryo.
An embryologist will monitor the development of the embryos over the next 6 days, after which they may choose a suitable embryo for implantation. During ICSI Procedure, the doctor extracts the eggs and injects a single sperm directly into an egg. They may do this if there is a problem with the sperm or if past attempts at IVF Cycle have not resulted in fertilization. The doctor may use one embryo and freeze the others.
How To Freeze An Embryo?
The main aim of freezing embryos is to preserve them for later use. The biggest challenge is the water within the cells. When this water freezes, crystals can form and burst the cell.
Cryopreservation:
To prevent this from happening, the doctor uses a process called cryopreservation. It involves replacing the water in the cell with a substance called a cryoprotectant. The doctor then leaves the embryos to incubate in increasing levels of cryoprotectant before freezing them.
After removing most of the water, the doctor cools the embryo to its preservation state. They then use one of two freezing methods:
Slow freezing:
This involves placing the embryos in sealed tubes, then slowly lowering their temperature. It prevents the embryo’s cells from aging and reduces the risk of damage. However, slow freezing is time-consuming, and it requires expensive machinery.
Vitrification:
In this process, the doctor freezes the cryoprotected embryos so quickly that the water molecules do not have time to form ice crystals. This helps protect the embryos and increases their rate of survival during thawing.
After the process of freezing is complete, the doctor stores the embryos in liquid nitrogen.
Success rates of thawing frozen embryos:
The process of thawing an embryo after cryopreservation has a relatively high success rate, and research suggests that women who use thawed embryos have good chances of delivering healthy babies. According to a comparative study and review published in 2016, babies born after cryopreservation showed no increase in developmental abnormalities. However, the medical community still requires more long-term follow-up studies.
Some research indicates that, compared with slow freezing, vitrification increases an embryo’s chance of survival, both at the freezing stage and during thawing.
Who Can Benefit?
Embryo freezing may be a better option for certain groups, such as:
People with genetic disorders that affect reproduction
People who will soon undergo chemotherapy
People who take medications that affect fertility
How Long Can Embryos Stay Frozen?
In theory, a correctly frozen embryo can remain viable for any length of time.
The embryos remain in sealed containers at temperatures of -321ºF. At this temperature, almost no biological processes, such as aging, can occur.
There are examples of successful pregnancies resulting from eggs that people have stored for up to 10 years. No long-term research into embryo freezing exists because doctors have only been carrying out the procedure since 1983.
Some countries regulate the length of time that a person can store their embryos. Freezing and storage are expensive, and each clinic has its own rules about what happens if a person can no longer use their embryos or keep them frozen.
Frozen Or Fresh Embryos?
A study published in the International Journal of Reproductive Biomedicine looked at the results of over 1,000 instances of embryo transfer involving either fresh or frozen embryos.
The researchers found no statistical difference between the types of embryos, in terms of pregnancy rates or fetal health. The authors pointed out that people could use frozen, but not fresh, embryos for additional transfers in the future.
Other studies suggest that transferring frozen embryos may be more effective.
Results of research published in 2014 indicate that frozen embryo transfer might lead to a higher rate of pregnancy and better outcomes for both the woman and baby.
Freeze-All Cycles:
In a freeze-all cycle, a doctor extracts an embryo, freezes it, and stores it.
People may benefit from this process if they have a higher risk of ovarian stimulation syndrome. This is a rare and potentially dangerous condition that can arise when a person is receiving stimulating hormones to increase egg production. To reduce the risk of this condition, a doctor may recommend freezing the embryo and transferring it when the ovaries are no longer stimulated.
A doctor can also use a freeze-all cycle to test an embryo for a genetic disorder. This involves removing a few strands of DNA and testing the chromosomes. Embryos with a standard set of chromosomes are more likely to transfer successfully. Prescreening can ensure that future offspring have a lower chance of developing genetic diseases.
Conclusion:
Embryo freezing is relatively safe and often leads to a successful pregnancy and delivery.
Possible risks include a slightly higher chance of genetic abnormalities in the child. It is important to note that, because this is a new procedure, the long-term health effects are not yet clear.
Also, women who become pregnant at a later age have a higher risk of complications.
In addition, fertility treatment can lead to ovarian hyperstimulation syndrome. In fewer than 2 percent of cases, symptoms are severe, but they are unlikely to be life-threatening. Finally, treatment can be costly. However, it offers a wider range of options for people who wish or need to delay pregnancy, or who may otherwise be unable to conceive.