Over the years, you have heard many different conversations amongst friends and family about what takes to get pregnant. More than likely, 99% of those stories are myths and tall tales from different experiences that may have had a positive outcome; however, the science behind it was more than likely misstated. In order to really understand what it takes to get pregnant, you must first understand your ovarian fertility as a woman. Here is a quick deep dive into ovarian fertility that will assist you in understanding your fertility, the process to freeze your eggs, the vitrification technology and what makes a practice associated with Frozen Egg Bank Network unique and qualified to assist you ensure that you can increase your chances of getting pregnant when you are ready to do so.
NATURAL FERTILITY RATE OVER TIME
A woman’s fertility begins to decline slightly in her 20’s, but her ability to conceive remains high well into her early 30’s. On average, a woman will experience a decrease in the quality and quantity of her eggs which impacts her fertility potential by the mid 30’s and that decrease greatly accelerates by her late 30’s and early 40’s. By the age of 45, a woman’s fertility potential is nearly non-existent. A woman’s fertility potential is more commonly referred to as her ovarian potential.
As a woman ages, this decline in ovarian potential is largely a result of a decrease in the quality of eggs that are available. To better understand this decline, it is helpful to understand that a woman is born with all her eggs, known as primordial follicles, already present in her ovaries. New eggs are not generated over time. The healthiest eggs a woman has are the ones that are ovulated when she is young. These healthy eggs are combined with sperm to create an embryo. Once the sperm fertilizes the egg, it begins to divide, ultimately creating a cell mass which is the foundation for the development of a baby. The number of primordial follicles falls rapidly as a woman ages, and the eggs she ovulates as she gets older are more likely to be compromised producing embryos with chromosomal abnormalities. These abnormal embryos will either not implant or if they do implant will result in a non-viable pregnancy. Due to abnormal embryos the miscarriage rate rises from approximately 10-15% for a woman in her 20’s, to approximately 35% at 40, and 50% by the age of 44.
Your level of ovarian potential can vary at any given age due to genetic and environmental factors. In some cases, decreased ovarian function may be a reflection of a woman’s genetics. Environmental factors may also play a role in decreasing your ovarian potential. For example, smoking is known to be a factor that will significantly compromise ovarian function.
Your ovarian potential can be assessed by a sonogram and blood testing. A transvaginal sonogram or ultrasound is performed to visualize the ovaries and to count the number of small antral follicles present. Antral follicles measure three (3) to nine (9) mm and good ovarian potential is reflected by the presence of a larger number of antral follicles. On average, a 35-year-old would have approximately 15 antral follicles contained within both ovaries. Therefore, a 35-year-old woman with an antral follicle count of 20 would be considered to have above-average ovarian potential, while a woman with only 10 follicles would have below-average ovarian potential. These antral follicles produce Anti-Müllerian hormone, commonly referred to as AMH. Through blood testing, we can determine a woman’s AMH level. A woman with an increased number of antral follicles will produce more AMH and therefore have a higher AMH level. Women with a decreased ovarian potential will have a lower AMH level. In addition, early on in the menstrual cycle, the pituitary gland produces a hormone known as follicle-stimulating hormone called FSH to stimulate ovarian potential. If this is elevated early on in the menstrual cycle, this may be an indicator of decreased ovarian potential.
It is important to recognize that while ovarian function tests predict the number of follicles in the ovary, your age is a better reflection of your eggs’ quality. In other words, a 43-year-old woman who has a good ovarian reserve may produce many eggs, but the egg quality may be reduced. Conversely, a 33-year-old woman with decreased ovarian reserve may produce fewer eggs, but may have higher egg quality.
THE IVF PROCESS
To freeze your eggs, you will need to complete an IVF cycle. Typically birth control pills are utilized to regulate your cycle and ensure your ovaries are at rest. At the beginning of your cycle, synthetic hormones are used to stimulate the ovaries into action growing the eggs located inside your antral follicles. Hormone medication is self-administered or given by a friend via an injection done nightly in the buttocks. When the antral follicles reach the appropriate size, your nurse will tell you to take an injection which triggers the maturation of the eggs. This is commonly called the “trigger” shot which will occur approximately 36 hours prior to your egg collection. At that specific time, your eggs will be removed under anesthesia and by a trained physician.
Following the egg collection, most women feel sore but it passes within a couple of days. A very small percent of women may experience Ovarian Hyperstimulation Syndrome (OHSS); however, fewer women experience this than in years passed due to the growing popularity of using a drug called Lupron to trigger the egg maturation. As a result, your risk of hyperstimulation is reduced to under 1%; however, if you do experience any nausea or abnormal discomfort you will want to report it to your physician.
After egg collection, your eggs are frozen in the IVF laboratory by an experienced embryologist using the vitrification technique.
TECHNOLOGICAL ADVANCES IN EGG FREEZING
Historically, eggs have been very difficult to freeze until a new technology was developed called vitrification. The egg is a large cell and is therefore vulnerable to the development of ice crystals in the freezing process which ultimately damages the egg during the thawing process. Vitrification is a rapid freezing process that has revolutionized our ability to successfully freeze eggs. It is a technically demanding and fickle technology, therefore working with a program that has proven egg vitrification experience will maximize your likelihood of pregnancy success.
After egg collection, the eggs are equilibrated and then the surrounding granulosa cells are stripped off. The eggs are exposed to a series of cryoprotectants to dehydrate the egg and prepare the egg for vitrification. Once the eggs are ready for vitrification, they are placed on a small plastic device that holds and stores the eggs known as the straw. A tiny micro droplet of fluid is placed on top of the eggs. This is another crucial step that needs to be performed by an experienced embryologist. If the droplet is too large, the rate of freezing will be slower and the egg may be damaged. Conversely, if the droplet is too small, the rate of freezing may be too rapid and the egg may be damaged.
THE NUMBER OF EGGS TO FREEZE
Only a small percentage of eggs have the potential to create healthy baby. It is estimated that in a 35-year-old, approximately 15 eggs can produce one baby, and in a 40-year-old, approximately 25 eggs can produce one baby. It is important to bear this in mind when deciding how many eggs to freeze. This decision is also influenced by the number of children you wish to conceive. We emphasize that while egg freezing provides a good back-up plan, it does not guarantee a pregnancy.
Some women will freeze their eggs and not have a baby. This unfortunate result may be due to the poor ovarian potential of the eggs, the lack of survival due to technical issues in either the freezing or the thawing process, the eggs’ quality being compromised in the storage or shipping process, the quality of the sperm used and ultimately the uterine environment in which a resulting embryo is placed. While many women will be successful in having a baby, it is important to have realistic expectations and understand that freezing your eggs does not guarantee a successful outcome.
In experienced hands with healthy eggs, approximately 85% of eggs will survive the thaw, 70% of the eggs will fertilize, and depending on your age, about 20-30% of the embryos will develop to an advanced stage known as a blastocyst that has the best chance of implantation. It is estimated that a 35-year-old who stores 20 eggs will have approximately a 70-80% chance of having one child with those eggs and a 40% chance of having two children. The likelihood of having more children is increased moderately as the number of eggs increases. In an average egg freezing IVF cycle, approximately 13 mature eggs are frozen; this will vary significantly based on the woman’s ovarian reserve. It is generally recommended that women with ages ranging from 34 to 37-years-old freeze 20 eggs and women with ages ranging from 37 to 40-years-old try to freeze 30 eggs.
Since vitrification is relatively new for eggs, research is still lacking regarding the efficacy of long term storage in liquid nitrogen. Nonetheless, practical application is encouraging and the current school of thought is eggs can be stored indefinitely. We recommend that eggs be stored separate from embryos to minimize the risk they will be jostled or moved in the IVF laboratory. Eggs are fragile and require egg specific protocols in the laboratory and in the shipping process in order not to be damaged.
Consideration should be given to the short or long term storage of your eggs. Some clinics charge monthly or annual fees to maintain your eggs in liquid nitrogen. While there may be less expensive providers for egg maintenance, shipping eggs from place to place multiple times may compromise the integrity of your investment.
USE OF FROZEN EGGS
If you have frozen your eggs and decide to conceive, it is generally recommended that you try with your fresh eggs first. Your frozen eggs will be a good back-up, unless your doctor recommends they be the first line of treatment due to your age. Once thawed, your eggs will be inseminated using the intracytoplasmic sperm injection (ICSI) technique. This involves placing a single sperm into the cytoplasm of the egg. Some of the eggs will fertilize and develop into embryos.
Embryos may be placed back into the uterus during your natural cycle; however, it is generally recommended to use hormones to prepare the uterus to be receptive to the embryo’s implantation. This typically involves a sequence of estrogen medication to thicken up the lining and then progesterone to mature it. This sequence mirrors the sequence of hormones produced in your natural cycle.
Once the embryos develop, the stage and number of embryos transferred back into the uterus will depend on your desires, the embryo quality, the specific embryology laboratory and your IVF program’s approach.
Frozen Egg Bank Network was developed by Donor Egg Bank USA, which banks eggs for use by women who need an egg donor to conceive. This partnership has provided the Frozen Egg Bank Network and its clients access to fertility clinics with very important and proven experience in the technique of both egg freezing and egg thawing which increases your chance of pregnancy. The complex technology required necessitates very close quality control. It is not enough to know how to freeze eggs, it is equally important to be skilled in the thawing process. Very few programs have warmed a significant number of eggs to have mastered both the freeze and thaw technique like fertility clinics in the Frozen Egg Bank Network.
Donor Egg Bank USA has had experience with more than 2,000 thaws encompassing 30,000 donated eggs and this experience provides continual insight into the egg freezing process. If an embryology laboratory simply freezing eggs and stores them without thawing them, they are unable to verify the embryologist’s ability to consistently freeze eggs well.
The Frozen Egg Bank Network and its parent company Donor Egg Bank USA have developed the “Seal of Quality Assurance” – which ensures transparency as to the training and quality of a fertility practice. To receive and maintain the Seal, embryologists must be trained in both egg freeze and egg thaw using a protocol proven by Donor Egg Bank USA. Participating clinics pass a rigorous set of requirements and must demonstrate competence by achieving an 80% or better survival rate through a quarterly practice freeze using immature eggs.
Women, like you, who want to freeze your own eggs can be increasingly confident by working with physicians and embryologists who are experienced in freezing and thawing eggs. The Frozen Egg Bank Network was developed to give you the best chances of a future baby.