Freezing Sperm

Cryopreservation, aka freezing your sperm, gives men the opportunity to become biological fathers in times that their fertility is in jeopardy. Learn the science behind sperm freezing and things to think about when freezing your sperm.

Topics | Fertility Preservation | Freezing Sperm

In this Article...

  • Why Freeze Sperm?
  • How Cryopreservation Works
  • Things to Consider
  • Using Frozen Sperm

Male Fertility Preservation: Freezing Sperm

Cryopreservation, aka freezing your sperm, gives men the opportunity to become biological fathers in times that their fertility is in jeopardy. Most commonly, fertility preservation is offered to men who are diagnosed with cancer before undergoing treatment which is highly toxic to the reproductive system.

Why freeze sperm?

There are a number of situations where a man might want to consider freezing sperm as a means of protecting his future paternity.

Cancer: The number one reason men freeze sperm is when they’ve been diagnosed cancer. Most treatments for cancer are gondatoxic, aka they wipe out sperm production. Many cancer patients do recover fertility 2-3 years following treatment, but not all.

Vasectomy Backup Plan: You never know what the future holds. Each year, about 500,000 men opt for a vasectomy as a form of permanent birth control once their family is complete. More and more often, men find themselves wanting to have more children and getting a vasectomy reversal. Surgical techniques for reversing vasectomies have gotten pretty good and success rate is around 90% for most specialized urologists. Freezing sperm can give a man extra flexibility in the case the a vasectomy reversal is not successful or as a way of avoiding a reversal if the need arises.

Klinefelter Syndrome: Klinefelter syndrome is a genetic condition where a man has an extra copy of the X chromosome and causes most men to become azoospermic. Klinefelters affects fertility by causing the germ cells that create sperm to degenerate over time. The process begins in utero and continues through adulthood eventually causing azoospermia. If diagnosed during adolescence, patients with Klinefelter’s have a greater chance of biological fatherhood if they are able to freeze sperm.

Lifestyle reasons: Some other reasons that men consider freezing their sperm including having an occupation that exposes them to toxic chemical or delaying their families till they are in their late 40s. (Latest research shows that advanced paternal age, older than 45, increases risk of various conditions including down’s syndrome and autism).

How cryopreservation works

Cryopreservation has been around since 1949 when Christopher Polge discovered that adding glycerol to animal semen protected the cells and enabled them to be used for insemination after being frozen and thawed. Since then, scientists have been working to perfect techniques to preserve various tissues by freezing them at incredibly low temperatures.

Collecting a sample

The first step to preserving sperm is collecting a sample. For most men, this is done the traditional way — yep, plastic cups and dirty mags. But as much of the time circumstances surrounding fertility preservation are not typical. Boys may be just approaching adolescence or a man may be diagnosed with testicular cancer and already have a considerable loss of sperm production. There are a number of techniques developed to assist with sample collection — sorry, they don’t involve any hot nurses — but they will ensure that you are able to gather the highest number of healthy sperm possible.

A note to mothers

You are not alone. There are a lot of mothers out there who unexpectedly find themselves responsible for the future fertility of their son. This can be incredibly delicate as time is of the essence and you may or may not have yet had those important “conversations” with your boy. First, take a deep breath. Doctors and specialists trained in fertility preservation often are very easy going with young guys and are able to talk to them about the issues at hand in a way that doesn’t make them feel awkward or embarrassed. One thing to remember is that these conversations often need to be had without your presence. There is nothing more awkward than talking about your potential manhood in front of your mom. Doctors should be able to assess your son’s maturity and provide guidance as to the best path forward.


Now that we’ve gotten our sample, time for a little cool science. How does cryopreservation work? Basically, as temperatures lower, biological processes happen slower — this is why they recommend icing a sprained ankle to reduce swelling. At super low temperatures, biology halts all together, essentially stopping time. So, can I throw my pet goldfish in the freezer and thaw it out in a few months? As cool as that would be, unfortunately, no. Most of the time, freezing living things causes the formation of ice crystals both inside and outside of cells. These ice crystals interrupt cell function and cause cells to collapse or explode.

So how do they freeze sperm and bring it back to life? Scientists have discovered that by adding various cryoprotectants, aka antifreeze for cells, they are able to minimize the amount of ice crystals that form and preserve cellular function. They also discovered that by controlling the rate of cooling, they are also able to control the formation of ice crystals. To geek out more, here is a link to the wikipedia article on cyropreservation.

Things to consider

How much to freeze? The answer to this depends on a number of factors. How time sensitive is the situation? How much sperm do you produce and how healthy is it? How likely is a permanent loss of fertility? How easy is it to obtain a sample? Generally, more is better. Freezing a few samples creates a better possibility that more sperm will survive the freeze thaw process. Having more frozen sperm to work with provides options for assisted reproduction later on. For example, if you have multiple vials with several million sperm, you may be able to consider an IUI which is the least invasive form of assisted reproduction. However, if you aren’t able to get very many sperm, never fear, new modern techniques such as ICSI only require a handful of healthy sperm to achieve a pregnancy.

Another matter to discuss with your fertility preservation specialist is how you would like to break down the sample. You may choose to have a few vials with larger quantities of sperm or more vials with smaller numbers of sperm. Your doctor will have advice on how to best optimize your sample to give you the most flexibility in the future.

Using frozen sperm

So, how do you make a baby with frozen sperm? It depends on how much you have and how well they survive the freeze thaw process. If you have high numbers of motile sperm and your partner has normal fertility, it may be possible to try an inter-uterine insemination. For this, the sperm will be thawed. Motile sperm will be separated and placed into a nutrient rich fluid that will give them extra strength and then placed into your partners uterus where they should hopefully be able to swim up into the fallopian tube and find an egg, leading to a pregnancy.

If there are fewer sperm or if your partner has known fertility issues, then doctors will likely recommend a more controlled form of assisted reproduction such as IVF or ICSI. To learn more about these options read our article on assisted reproduction.


There are a growing number of resources to support men in preserving their fertility.

An amazing organization, Fertility within Reach, has partnered with the world renowned urologist Paul Turek to offer grants to men diagnosed with cancer to be able to afford fertility preservation. Learn more about their incredible Banking on the Future Program.
For those located in New England, Brown University in Rhode Island has one of the leading fertility preservation programs lead by urologist Dr. Kathleen Hwang.

To learn more, check out our Roadshow Episode on Fertility Preservation


Osterberg EC1, Ramasamy R1, Masson P2, Brannigan RE2. Current practices in fertility preservation in male cancer patients, Urol Ann. 2014 Jan;6(1):13-17.
González C1, Boada M, Devesa M, Veiga A. Concise review: fertility preservation: an update. Stem Cells Transl Med. 2012 Sep;1(9):668-72. doi: 10.5966/sctm.2012-0076. Epub 2012 Sep 7.

Sara SDx

Sara SDx

Editor of Don't Cook your Balls, Co-Founder of, Health Coach and Men's Health Advocate. Passionate about sperm, men's health and helping people build their families.
Sara SDx

Author: Sara SDx

Editor of Don't Cook your Balls, Co-Founder of, Health Coach and Men's Health Advocate. Passionate about sperm, men's health and helping people build their families.

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