Pu­blished: 10. Fe­bruary 2022 | Up­dated: 14. De­cember 2023 Author: An­drea Helten | Re­viewed by An­drea Helten

So­cial free­zing: suc­cess rates 

What is the ideal age to have my eggs frozen?

This is a ques­tion women often ask in the con­text of so­cial free­zing. A sim­pli­fied answer to this would be that it is ge­ne­rally better to do it at a younger age than at a later age.

Ho­wever, it is not quite that simple. Both the quan­tity (“egg re­serve”) and the qua­lity of the eggs do not de­velop li­ne­arly with age. In order to better un­der­stand the li­keli­hood of suc­cess with so­cial free­zing, it is worth re­cal­ling the pro­ce­dure: After hor­monal sti­mu­la­tion of the ova­ries, the eggs are re­moved and then frozen at minus 196 de­grees Cel­sius. Ac­cor­dingly, there are two es­sen­tial steps in this pro­cess that de­ter­mine the sub­se­quent pro­ba­bi­lity of suc­cess of a pregnancy from cryo­p­re­served eggs: 1. the re­trieval and 2. the free­zing of the eggs.

So­cial Free­zing: How many eggs are ne­ces­sary?

If 20 ma­ture eggs are re­trieved from a 34-year-old woman, there is a 90% chance of at least one birth.

One of the most im­portant sta­tis­tical suc­cess fac­tors is the age of the pa­tient at the time of egg re­trieval. This is due to the fact that the qua­lity of the eggs de­creases with in­cre­asing age — in me­dical terms, this is re­ferred to as the “eu­ploidy of the cell or­ga­nisms”.

In ad­di­tion, the na­tural egg re­serve de­creases with in­cre­asing age, which is why more cy­cles are then needed to re­trieve the same number of eggs. A cri­tical age in terms of oo­cyte re­serve is often con­sidered to be around the ago of 35, as from this point on­wards the rate of na­tural births de­creases dis­pro­por­tio­na­tely [1]. In ge­neral, it is re­com­mended to re­trieve at least 10–20 eggs for so­cial free­zing. Ac­cor­ding to a 2017 study of 520 ICSI cy­cles, women aged 34, 37 and 42 have a 90%, 75% and 37% chance of at least one suc­cessful live birth with 20 frozen eggs, re­spec­tively. A 20-year-old woman even has a 94% pro­ba­bi­lity with 20 frozen eggs [1].


The case when pa­ti­ents wish to have se­veral births based on the frozen eggs can be con­sidered si­mi­larly. Again as­suming 20 frozen eggs are re­trieved, a 34-year-old woman has a 66% chance of ha­ving at least 2 births. For a 42-year-old woman, on the other hand, the chance is only 7% [1].

If at least three births are to be achieved, the pro­ba­bi­lity of the 34-year-old woman de­creases to 38% and the pro­ba­bi­lity of the 42-year-old is about 1% [1].

Overall, a clear cor­re­la­tion can be de­mons­trated bet­ween the age at the time of egg coll­ec­tion and the pro­ba­bi­lity of suc­cess of a sub­se­quent pregnancy from so­cial free­zing. Of course, it should be noted that these are sta­tis­tical mean va­lues, which in prac­tice vary from person to person. Si­mi­larly, re­gard­less of age, there is no gua­rantee of suc­cess with so­cial free­zing for a sub­se­quent pregnancy.

So­cial Free­zing: Me­thods of free­zing

About 92% of eggs frozen with vi­tri­fi­ca­tion sur­vive.

There are fur­ther dif­fe­rences in suc­cess rates due to the me­thod of free­zing the eggs. A di­stinc­tion is made here bet­ween so-called “slow free­zing” and vi­tri­fi­ca­tion. The two me­thods differ pri­ma­rily in the speed at which the eggs are frozen.

In slow free­zing, the re­trieved oo­cytes are cooled by about 2 — 3 de­grees Cel­sius per mi­nute over a longer pe­riod of time until they reach the re­quired minus 196 de­grees Cel­sius. This low final tem­pe­ra­ture is ne­ces­sary to stop the bio­lo­gical pro­cesses in the oo­cytes and make long sto­rage pos­sible wi­t­hout the loss of qua­lity.

In vi­tri­fi­ca­tion (also called “flash free­zing”), the eggs are im­mersed in li­quid ni­trogen, which al­lows them to be frozen at minus 196 de­grees Cel­sius wi­thin mi­nutes. For egg free­zing, speed is a cru­cial suc­cess factor: eggs lar­gely con­sist of water, which is why it is im­portant to pre­vent crystal­li­sa­tion of the li­quid du­ring free­zing. Ac­cor­dingly, vi­tri­fi­ca­tion is cle­arly the more pro­mi­sing me­thod, which is why it has be­come wi­dely ac­cepted in re­cent years [2].

In sum­mary, the age of the woman, which is ide­ally below 35 years, in com­bi­na­tion with the me­thod of free­zing (vi­tri­fi­ca­tion) are de­cisive fac­tors for in­cre­asing the pro­ba­bi­lity of suc­cess of a sub­se­quent pregnancy th­rough so­cial free­zing.

» So­cial Free­zing: Re­asons and Ac­cep­tance

About Fer­tilly

At Fer­tilly, we have made it our mis­sion to ac­com­pany cou­ples (ho­mo­se­xual and he­te­ro­se­xual) and sin­gles on the way to ful­fil­ling their child wish. In doing so, it is im­portant to us to create trans­pa­rency in the area of fer­ti­lity ser­vices, to pro­vide in­for­ma­tion and know­ledge on the to­pics of pregnancy and fer­ti­lity and to help you to find the most sui­table Fer­ti­lity Center. Th­rough co­ope­ra­tion with first-class Fer­ti­lity Cen­tres and cli­nics in Eu­rope, en­qui­ries about Fer­tilly are given pre­fe­ren­tial tre­at­ment. This means that our pa­ti­ents avoid the usually long wai­ting times and get ap­point­ments more quickly.

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1. Goldman RH, e. (2017): Pre­dic­ting the li­keli­hood ofl ive birth for elec­tive oo­cyte cryo­p­re­ser­va­tion: a coun­seling tool for phy­si­cians and pa­ti­ents. — PubMed — NCBI. Re­trieved from https://www.ncbi.nlm.nih.gov/pubmed/28166330
2. Cobo, A., García-Ve­lasco, J., Coello, A., Dom­ingo, J.,Pellicer, A., & Re­mohí, J. (2016): Oo­cyte vi­tri­fi­ca­tion as an ef­fi­cient op­tion for elec­tive fer­ti­lity pre­ser­va­tion. — PubMed — NCBI. Re­trieved from https://www.ncbi.nlm.nih.gov/pubmed/26688429