Information for children, teenagers and families


Male fertility

Nearly all (98%) of men with CF are infertile as they are born with bilateral absent vas deferens (the tubes that allow sperm to leave the testes). This can be confirmed on semen analysis when the patient is old enough (generally the mid-late teenage years and onwards). If general health is good, sexual performance and function are normal. Other sexual health risks unrelated to CF, such as sexually transmitted infections, are still present and protection such as condoms may therefore still be needed.

Assisted fertility techniques are available to allow men with CF to have children. One of these is called ICSI – intracytoplasmic sperm injection. This procedure involves injecting a single sperm directly into an egg in order to fertilise it. The fertilised egg is then transferred to the woman’s womb. Because a man with CF is guaranteed to pass on a CF mutation to his child, it is usually recommended that his partner is screened for CF mutations.

Female fertility

Women with CF have normal reproductive tracts but they are still less fertile than healthy women. This is probably due to the fact that the cervical mucus in women with CF is thick and sticky and does not vary with ovulation. This makes it difficult for sperm to penetrate the mucus through to the uterus and beyond. Poor nutrition and severe disease can also cause a lack of periods and means the ovaries do not release eggs as they should do.

Better lung health and nutrition means that women with CF today have higher fertility than in the past and therefore contraception must still be used by all sexually active women who do not want to get pregnant. Antibiotics can reduce the effectiveness of the pill. The CF trust publishes a leaflet on relationships, some of which deals with sex, contraception and pregnancy. This is available here