Cystic Fibrosis and Male Fertility


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Cystic Fibrosis is a condition that affects around 100,000 people around the world – and 50% of those are men. The condition has far reaching effects on the health and lifestyle of people who suffer from it – but can it affect your fertility?

What is Cystic Fibrosis?

Cystic Fibrosis (sometimes known as CF) is a medical condition which results in severe damage to the lungs as well as impacting the digestive system and other organs in the body. The disorder affects the production of mucus, sweat and digestive juices in the stomach.

For people without CF, these fluids are usually thin and slippery. However, those with cystic fibrosis have a defective gene that causes these fluids to become thick and sticky. This causes a build up of mucus in the lungs and in the pancreas, and means that tubes, ducts and passageways become clogged up. This makes it hard for them to breathe and also impacts other bodily functions.

Respiratory issues are caused by a buildup of mucus on the lungs, and people with CF often find that they have shortness of breath and struggle with recurrent chest infections. People with CF also often have various digestive issues – this is because mucus also clogs the pancreas stopping enzymes needed for proper digestion from reaching the gut.

People with CF sadly have a lower life expectancy, however thanks to medical advancements they are living longer and some manage to lead relatively normal lives – although they do require daily care and regular care and medical interventions.


Is Cystic Fibrosis hereditary?

Cystic Fibrosis is a hereditary disorder, caused by a defective gene that affects the way salt and water move in and out of cells. You cannot ‘catch’ cystic fibrosis, but instead are born with the condition, if both parents are carriers of the faulty gene.

It’s estimated that 1 in 25 people in the UK are carriers of the recessive CF gene. That doesn’t necessarily mean that a parent will have Cystic Fibrosis themselves.

If both parents are carriers, there’s a:

  • A 50% chance the child will inherit a faulty gene from one parent and become a carrier of the gene
  • A 25% chance the child won’t inherit any faulty genes and won’t have cystic fibrosis or be able to pass it on
  • A 25% chance the child will inherit the faulty gene from both parents and have cystic fibrosis themselves

If one parent has cystic fibrosis and the other is a carrier, there’s a:

  • 50% chance the child will be a carrier of the faulty gene but won’t have the condition
  • 50% chance the child will have cystic fibrosis

Does Cystic Fibrosis impact fertility in women?

Generally speaking, women with CF are still fertile and the vast majority are able to conceive naturally with 12 months of trying. However, there are a couple of side effects of the condition that can make it a little harder.

Firstly, their cervical mucus is often thicker than the mucus of someone who doesn’t have the condition. Cervical mucus plays an important role in helping sperm cells swim towards the egg, and when it is thick and sticky it can make it more difficult for them to get there!

The digestive issues associated with CF can also cause issues with ovulation, and some women with CF notice that they have irregular menstrual cycles.

Whilst these two factors can contribute to a more difficult TTC journey it is still definitely possible to get pregnant and give birth to a healthy baby if you have Cystic Fibrosis. Yoru medical team and fertility specialists will be able to advise you on the best plan of action if you are struggling.

Does Cystic Fibrosis impact fertility in men?

Unfortunately for men, the issues around Cystic Fibrosis and fertility are more complex. Over 97% of men with Cystic Fibrosis are classed as infertile – although 90% of them can produce healthy sperm. So what is causing the fertility issues?

Infertility in men with cystic fibrosis is almost always attributed to a lack of a vital part of the male reproductive system – the Vas Deferens. The Vas Deferens is a long canal connecting the epididymis (a coiled tube that stores sperm after it’s produced in the testicles) into the pelvic cavity. The role of the Vas Deferens is to transport mature sperm calls from the epididymis into the urethra ready for ejaculation.

If you don’t have a Vas Deferens, you will likely have a condition known as congenital bilateral absence of the vas deferens (CBAVD). This is extremely common in men with Cystic Fibrosis. If you have CBAVD, then even if you are producing healthy sperm, there is no way for them to make it into your ejaculate, which means there will be no sperm cells in your semen sample (and no sperm cells able to fertilise an egg during sex).


Fertility treatment options for men with Cystic Fibrosis

Having no sperm cells in your semen is obviously going to make a fertility journey more difficult. But the good news is that if you are producing healthy sperm cells, it is possible to have biological children of your own – you just will need a helping hand.

Surgical sperm extraction can remove sperm cells from the testicles or epididymus and these sperm can be used in assisted fertility treatments such as ICSI and IVF.

There are various surgical options for extracting sperm cells including.

MESA – Microsurgical Epididymal Sperm Aspiration. Surgery done under general anaesthetic to remove sperm cells directly from the epididymis.
PESA – Percutaneous Epididymal Sperm Aspiration – similar to MESA but less complicated and less expensive, a needle is used to extract the sperm so it can be done under local anaesthetic.
TESE – Testicular Sperm Extraction – Surgery where tissues is taken directly from the testicles and sperm cells extracted.
TESA – Testicular Sperm Aspiration – Similar to TESE but is done using a needle so is less intrusive and can be done with local anaesthetic.

If healthy sperm cells are found during any of the above procedures, then they can be used in fertility treatments and you are one step closer to building your family.


What if I’m a carrier of CF genes? Will this affect my fertility?

If you are a carrier of the mutated gene that causes Cystic Fibrosis, there is a chance your fertility could be affected – even if you have no other symptoms of the condition. Research has indicated that men with the condition Azoospermia (no sperm cells in their semen) are twice as likely to be carriers of the mutated CF gene. Some men who carry this recessive gene may also have CBAVD (no Vas Deferens).

Therefore, if you discover you have Azoospermia, it’s advisable to get screened for the CF gene. Likewise, if you discover you are a carrier of the CF gene, you should definitely look into getting your sperm tested. Many people show no outward signs of Azoospermia and only discover they have no sperm in their ejeculate once they start trying for s baby.

If you want to take a proactive approach to your health and fertility, our at-home sperm test can help. Learn more about our men’s fertility test and find out your Total Motile Sperm Count.

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Wearing tight pants and underwear

Studies show that men who wear looser underwear have higher sperm concentration and total sperm count compared to men who wear tighter underwear. So, lose the tight clothes and wear something loose to give your testicles some air.

CONCLUSION: learn more about how heat can affect sperm quality here.


Besides higher mortality rate and various diseases, stress is associated with low sperm quality. Stress is known to be associated with lower testosterone levels and oxidative stress with both playing an essential role in producing and maintaining healthy sperm cells.

CONCLUSION: If you feel stressed, we recommend you get some help so you can have a balanced mental health. For a stress management guide, download the ExSeed app for free and start your personalized action plan today.

Physical activity

Scientific studies show that men who are physically active have better semen parameters than men who are inactive. Fertility specialists also state that regular physical activity has beneficial impact on sperm fertility parameters and such a lifestyle can enhance the fertility status of men.

Prioritizing exercise can help improve your overall health and result in healthy, fast swimming sperm cells that have good chances of fertilizing an egg.

CONCLUSION: Try incorporating exercise in your weekly schedule to you ensure exercising at least twice weekly. We recommend a combination of cardio training and strength exercise. Read more about exercise and male fertility on our blog.


Fast Food
Processed foods damage the health of sperm-producing cells and cause oxidative stress, which lead to poorer sperm quality. Heavy consumption of junk food (every week) can increase the likelihood of infertility since men who consume vast amounts of unhealthy food are at risk of having poor sperm quality. Besides harming your fertility, junk food enlarges your waistline, harms your cardiovascular system, kidneys, and more.

Eating more fruit and vegetables can increase your sperm concentration and motility. It’s important that you consume a healthy diet filled with antioxidants and that you eat vegetables every day. Foods such as apricots and red bell peppers are high in vitamin A, which improves male fertility by nurturing healthier sperm. Men who are deficient in this vitamin tend to have slow and sluggish sperm.

Sugary snacks/beverages: several times a week Excessive consumption of high sugar items can lead to oxidative stress, which negatively impacts testosterone levels and sperm motility. Sugary snacks and beverages are also highly associated with obesity and low fertility.
CONCLUSION: To boost sperm quality, stay away from fast food, processed food, and sugary snacks or beverages. You need to implement a healthy prudent diet filled with necessary superfoods needed for good sperm production. Check out our guide to Male Fertility Superfoods. For personalized guidance and support on how you can start improving your sperm health, check out the Bootcamp.


Direct heat can inhibit optimal sperm production and cause Sperm DNA damage. Sperm cells like environments that are a couple of degrees lower than body temperature. Avoid overheating from warm blankets, seat warmers, heat from your laptop, hot showers, and saunas.

Cigarette smoking

The exposure to tobacco smoke has significant negative effects on semen quality. The damage of cigarettes and nicotine of course depends on how many cigarettes you smoke per day and for how long, but even low usage (up to 10 cigarettes / day) can inhibit healthy sperm production.  

CONCLUSION: Stay as far away from cigarette smoking as possible if you care about your general health and your fertility. Read more here.

Cell phone

When you have your cell phone in your front pocket, your testicles are exposed to electromagnetic radiation, which studies have shown to damage the sperm cells. Put your phone in the back pocket of your pants or in your jacket pocket.


There is a clear association between obesity and reduced sperm quality. At least part of the reason for this is that obese men may have abnormal reproductive hormonal profiles, which can impair sperm production and lead to infertility. 

A BMI higher than 30 can lead to several processes in the body (overheating, increase in oxidative stress in the testes, sperm DNA damage, erectile dysfunction) that can have a negative impact on male fertility. This can result in problems when trying to conceive.  

CONCLUSION: BMI is one of the risk factors that influence semen quality and, for example, sperm motility.  


A beer or glass of wine now and then do not really harm sperm quality. But excess alcohol drinking (more than 20 units per week) can reduce the production of normally formed sperm needed for a successful pregnancy.

CONCLUSION: If you want to stay safe, stay under 14 units of alcohol per week. For more information on how alcohol can affect male fertility, take a look at our blog: “Alcohol and Sperm Quality”.


Studies show that women younger than 35 and men younger than 40 have a better chance of getting pregnant. Men can produce sperm cells almost through their entire life, but the sperm cell DNA is more fragile and prone to damage after the age of 40.

As men age, their testes tend to get smaller and softer resulting in a decline in sperm quality and production. These changes are partly because of an age-related decrease in testosterone level, which plays a very important role in sperm

production. Higher male age (>40 years) is not only associated with a decline in sperm production but also with increased sperm DNA fragmentation and worsened morphology (shape) and motility (movement). These negative effects make the sperm cells less qualified for egg fertilization.

CONCLUSION: with an age under 40, you shouldn’t have to worry much about age as a factor in itself. However, studies have shown a slow decline after the age of 30-35 years

and if you are above 40 years of age, your sperm quality can be affected due to increased sperm DNA damage resulting in a decrease of sperm motility and concentration. Remember that you cannot evaluate the quality of a sperm sample by just looking at it – this requires a sperm analysis.