Genetics
CF is an autosomal recessive disorder, which means that an individual must have two copies of an abnormal “CF gene” in order to have the disease. People with only one copy are carriers but will not have CF. If one carrier has children with another carrier, there is a 50 percent chance that their children will have CF. If two CF patients have children, then all of the children will have CF. If someone with CF has children with someone who is not a carrier, all of the children will be carriers but none will have CF. With such a high chance of passing on CF genes, you should know your partner’s genetic makeup before starting a family. Many different tests can determine if your future spouse is a carrier.

Fertility
It is very important for female CF patients to know that they have relatively normal fertility and can become pregnant. Although female patients may think they are too sick to have children, this is often not true. Many women with CF will have a full-term pregnancy. Whether a woman is healthy enough to care for a child is another issue.

Women considering birth control should discuss their intentions with a gynecologist as many antibiotics prescribed to CF patients can decrease the effectiveness of oral contraceptives. Most males with CF cannot father children without medical assistance. Over 90 percent of boys with CF are missing the vas deferens––the tubes that connect the testis to the urethra. So, although sperm is made, it cannot leave the testis. Because 10 percent of male patients will be fertile, all male patients should have semen analysis.