Depending on your age, starting a family might seem like a far off thing, for others it may be something you are thinking about now.

Whatever your circumstance you may be interested in finding out more about fertility and how men with CF can be affected.

Men with CF produce sperm normally and their testes produce normal levels of testosterone (the male sex hormone).

Testosterone is absorbed directly into the blood and is responsible for gains in muscle mass and sexual feelings. Men with CF have normal levels of testosterone and therefore normal sexual developmental and sexual function, including erections.

Approximately 98% of men with CF have problems with the development of the vas deferens, the duct that leads sperm from where it is produced in the testes to where it is stored prior to ejaculation. Therefore the ejaculate (semen) produced does not contain sperm. This means that most men with CF are infertile i.e. they cannot conceive a child through sexual intercourse. Men with CF are still able to have biological children using assisted reproductive technology.

Finding out if you are fertile

As well as sperm, semen contains fluid made by glands called seminal vesicles. In men with CF, these glands don’t function normally and are sometimes absent. This means that men with CF may not experience nocturnal emissions (“wet dreams”). The ejaculate will contain fluid produced in other parts of the reproductive tract. Even though the volume of fluid may be reduced, sexual function is not affected. Sex will feel the same as it does for men who don’t have CF; it will also feel the same for their partners.

It is possible to find out if you are fertile or not through a test called semen analysis, which involves producing ejaculate by masturbation. This is then examined in a laboratory to look for sperm. You can ask your CF team or your GP if you are interested in having this test. It can be a hard thing to face, but for many it can be better to know one way or another so you can process it.

There is no right time to have semen analysis. Some people want to know if they are fertile in adolescence, and other people may choose to wait until they are thinking about having children.

Before you have been tested and know about your fertility, it is best to protect any female partners from pregnancy – just in case. It is also important to remember that even if sex won’t lead to pregnancy, it is still possible to contract a sexually transmitted infection (STI). It is important to use condoms to protect from STIs.

For men with CF there are options for becoming a parent

There are a number of options available to men with CF who want to have children. For example, the sperm can be taken directly from the testis under local or general anaesthetic in a procedure known as microscopic epididymal sperm aspiration (MESA). The female egg is retrieved from the ovary using invitro fertilisation (IVF) techniques. The egg is then fertilised with the sperm, using intracytoplasmic sperm injection (ICSI), and the fertilised embryo is then placed into the woman’s uterus (womb). Artificial insemination with donor sperm is also possible and some men with CF choose to adopt children.

Genetic counselling is also important

Your biological children will inherit one copy of the CF gene from you, but they will not have CF unless they also inherit a copy of the CF gene from their mother. The potential mother can have genetic testing to find out if she is a carrier of a CF gene. This will tell you what the chance is that your child will have CF, which may affect your choices about how you start a family. It is also possible to have the foetus tested for CF during early pregnancy, using procedures known as chorionic villus sampling or amniocentesis.