Understanding how many eggs you should freeze in one cycle, egg freezing calculators, and how many eggs are enough for one baby
October 16, 2023
Understanding how many eggs you should freeze in one cycle, egg freezing calculators, and how many eggs are enough for one baby
Egg freezing has become a popular option for women who wish to preserve their fertility. One of the most pressing questions in this process is: How many eggs should you freeze? The answer to this question depends on various factors such as age, health, and personal goals. In this article, we will discuss how to calculate the number of eggs to freeze and factors to consider when determining the ideal number of eggs to freeze.
Overall, the most important thing to keep in mind is that the number of eggs retrieved is not equal to the number of babies born. To better understand why you need more eggs to get to a pregnancy, it is worth looking into the egg freezing and IVF process overall.
Not all of the eggs that will be retrieved will be mature, and only mature eggs will be frozen. At your first appointment, when your fertility doctor evaluates your ovarian reserve and does the fertility testing, they would be able to say how many eggs they expect to retrieve. That number will depend on the number of follicles tin your ovaries, your testing results and age, as well as a medication protocol that is used.
Below is the average number of eggs frozen depending on your age:
Not all of the eggs will survive the thawing process. On average, 80-90% of eggs frozen will survive the thaw; frozen embryos have a slightly higher survival rate of 85-90%.
When it comes to fertilization, in a good lab, if there is no issue with the sperm, the fertilization rate is over 75%. If there is a known issue that affects the quality of the eggs or sperm, the fertilization rate can be lower.
After fertilization, embryos are cultured in the lab. Only some of them will form a blastocyst and grow to the stage when the embryo can be transferred. The blastocyst stage is the last stage the embryos can grow into outside of the human body. The blastocyst development rate depends on the fertility clinic's embryo lab quality and your age. The minimum expected for 35-39 y.o is 45%, and best practice is over 65%.
Depending on the age, only a certain percentage of embryos developed into the blastocyst stage will be genetically normal. On average, if you are under 35 years old when you freeze eggs, your embryos developed during the cycle have around 55% chance of being genetically normal (euploid), with this number steadily dropping to 0 at the age of 45.
Good quality euploid embryos have higher implantation rates, with an average implantation rate of 66% for Day-5 embryos and 55% for Day-6 embryos.
The success rate (how many babies are born) per transfer varies from clinic to clinic. On average, for patients under 35 years old, the average success rate per transfer is around 50% for women under 35, based on national data published by the CDC.
While egg freezing is not a guarantee, and there is no perfect formula that will tell you how many healthy embryos and kids you would be able to get from your frozen eggs, egg freezing calculators help to understand your approximate chances with a certain number of eggs frozen at a specific age. One of these calculators that has gained recognition for its accuracy and reliability is the BWH Egg Freezing Calculator, developed by Brigham and Women's Hospital.
Based on the BWH live-birth probability formula and an average number of eggs frozen per cycle for a certain age, we calculated how many cycles you may need to get to 75% live-birth probability. It's important to take into account your actual number and family plans to understand if that would be enough for your individual case:
Factors to Consider
Age: Age is a critical factor in determining how many eggs should be frozen. As women age, their ovarian reserve (the number and quality of eggs) decreases, making it more challenging to conceive naturally. Generally, the younger you are when you freeze your eggs, the fewer you may need to achieve a successful pregnancy later on.
Family Goals: Your reproductive goals play a significant role in determining the number of eggs you should freeze. For example, if you aim to have one child, your egg freezing target may differ from someone who hopes to have multiple children.
Ovarian Reserve: Your ovarian reserve is a measure of your egg quantity. A fertility specialist can assess this through tests such as the anti-Müllerian hormone (AMH) test and antral follicle count. Women with a lower ovarian reserve may need to have multiple cycles to improve their chances of success.
Success Rates: It's important to consider the success rates of egg freezing when deciding on the number of eggs to freeze. While the number of eggs frozen matters, it's also essential to keep in mind that not all frozen eggs will result in a successful pregnancy.
Conclusion
Egg freezing is a promising option for those who want to preserve their fertility and have children later in life. Determining the ideal number of eggs to freeze is a complex decision influenced by various factors, including age, family goals, and ovarian reserve.. It's crucial to remember that recommendations are not one-size-fits-all, and consulting with a fertility specialist is essential to make informed decisions about your egg freezing journey.
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