How Many Eggs Do I Need to Freeze to Secure My Fertility

As a fertility doctor, I have daily consultations with women looking to preserve their fertility and half of my practice is dedicated to egg freezing!

With growing awareness on the effects of age and fertility, and women delaying childbearing, egg freezing has become very popular! One of the most common questions patients ask me is: “How many eggs do I actually need to feel secure about my ability to have kids in the future?” The answer is nuanced, as it depends on several factors, including age, egg quality, and personal fertility goals. In this post, we’ll explore what you need to know to make informed decisions about egg freezing.

Age and Egg Quality: Why They Matter

Age is one of the most significant factors in determining how many eggs you may need. Women are born with all the eggs they will ever have, and this reserve naturally declines over time. Not only does the quantity of eggs decrease, but the quality does as well. Younger eggs tend to be more chromosomally normal, while older eggs are at a higher risk of chromosomal abnormalities, which can lead to lower likelihood of conception and higher chance of miscarriage.

•<35: Generally, a higher percentage of eggs retrieved from women under 35 are chromosomally normal, which means that you may need fewer eggs to achieve a successful pregnancy in the future.

•35 and Over: As women age, the number of eggs retrieved that will lead to a live birth are decreased. This decrease becomes significantly more pronounced as a woman approaches her late 30’s and early 40’s. Freezing more eggs can help offset this decline in quality.

How Many Eggs Should You Aim to Freeze?

A number of studies (though data is still somewhat limited) have demonstrated that 15 to 20 mature eggs can give a good chance of having at least one child in the future. This number accounts for the natural attrition that occurs from freezing, thawing, fertilization, and embryo development.

•If You’re Under 35: Eggs are of much higher quality and therefore are more likely to survive the thaw (most studies and many labs quote 95% survival rate) and lead to a blastocyst (a blastocyst is an early, day 5-7 embryo). While this isn’t the most evidence based tool, there are egg freezing calculators that will provide chance of one, two and three live births based on number of eggs frozen and female age. Though generally speaking, Freezing about 10–15 eggs might provide a good chance of a future pregnancy, but 15–20 eggs may offer even more security, especially if you hope to have more than one child.

•If You’re over 35: More eggs are needed to provide similar odds of live birth to women under 35. The challenging piece is that the older you are, the more eggs you need however the more difficult it is to acquire more eggs from a single cycle since ovarian reserve is reduced. Unfortunately we cannot stimulate follicles in the resting stage that are not available for stimulation.

Unrelated to egg freezing, one recent study sought to determine number of eggs needed, based on female age, for obtaining one chromosomally normal embryo in an IVF cycle. Now IVF is different from egg freezing since some eggs are lost in the thaw process, and this is just one study showing averages but it helps to understand the inefficiency of human reproduction and to help set expectations. The figure below outlines the mean egg number needed based on age.

In another, unpublished study of 450 patients who had previously frozen their eggs, researchers analyzed the rates of thaw survival and the average number of frozen-thawed eggs required to obtain one euploid embryo (a chromosomally normal embryo) outlined in the table below. This study offers a more practical perspective for patients considering egg freezing, as it takes into account the potential loss of eggs during the freezing and thawing process, which is not a factor in traditional IVF cycles. In the table below, the term “M2s” refers to mature eggs, or metaphase II oocytes. These findings are valuable for counseling patients on how many eggs they may need to freeze to reach their family-planning goals. It also helps set realistic expectations regarding the number of egg-freezing cycles that may be necessary, depending on the number of eggs retrieved per cycle—a quantity that can often be estimated by the patient’s antral follicle count. While more studies are needed to provide more evidence based data, this is a great start to help guide conversations based on a person’s goals.

One Cycle Might Not Be Enough

The average number of eggs retrieved per cycle varies based on age and individual ovarian reserve. Women under 35 might retrieve an average of 10–20 eggs per cycle, but sometimes younger women may have very few eggs retrieved and conversely some older women will have a significantly higher number of eggs retrieved (>30)- these are the exceptions, not the rule. Having a real and honest conversation with your doctor can help guide whether you decide to pursue multiple cycles to help achieve your fertility goals.

What Are Your Personal Fertility Goals?

When determining how many eggs to freeze, it’s essential to consider your personal goals. If you hope to have multiple children in the future, you might consider freezing a larger quantity of eggs. Conversely, if you’re uncertain about whether you want children or are only aiming for one child, you may be comfortable with a smaller number of frozen eggs.

There is no one-size-fits-all answer when it comes to the number of eggs to freeze for fertility preservation. By understanding the impact of age, egg quality, and your personal goals, you can make an empowered choice about your fertility. Remember, everyone’s journey to preserving their fertility is unique.