What causes cystic fibrosis?
Cystic fibrosis is a genetic disorder. Some genes do not function properly because there is a mistake in them. If a gene has a mistake, it is said to be altered or changed. For some diseases — like CF — both genes of the pair have to be altered for a person to have the disease.

Could I be a carrier of cystic fibrosis?
Yes. You could be a carrier of CF even if no one in your family has CF and even if you already have children without CF.

If my test result is normal, could I still be a carrier?
Yes. There are some mutations in the CF gene that the current test cannot find.

However, these unknown CF mutations are rare.

If the test shows I am a carrier, what should I do?
If the test shows that you are a carrier, the next step is to test the baby's father. Both parents must be carriers for the baby to have CF.

What if both my partner and I are cystic fibrosis carriers?
If two people who are both carriers have a child, that child may have CF. When two carriers have a child together, there is a 1-in-4 (25 percent) chance with each pregnancy that the child will have CF.

If I had cystic fibrosis testing, do I need it again?
If the test shows you are a carrier, the result is definite and will not change. However, if you are a carrier and have a new partner for a future pregnancy, testing should be considered for that new partner.

How do I decide whether or not to have carrier testing?
After learning about CF carrier testing, some people decide to have testing, and others decide against it.

Possible reasons to be tested:

• If CF seems like a very serious disorder to you
• If the chance of being a CF carrier seems high to you; this may be especially likely if a member of your family or your partner's family has CF or is a known carrier
• If you and the baby's father would consider amniocentesis or CVS
• Because test results are usually reassuring

Possible reasons not to be tested:

• If CF does not seem like a very serious disorder to you
• If the chance of being a CF carrier seems low to you; this may be especially likely if you are Asian American or African American
• If you and the baby's father would never consider having amniocentesis or CVS
• Because the test is not perfect and will not identify all carriers

This excerpt from ACOG's Patient Education Pamphlet is provided for your information. It is not medical advice and should not be relied upon as a substitute for visiting your doctor. If you need medical care, have any questions, or wish to receive the full text of this Patient Education Pamphlet, please contact your obstetrician-gynecologist.

What is the chance that my baby will have cystic fibrosis?
There is a 1-in-4 (25 percent) chance that the baby will have CF. Stated another way, there is a 3-in-4 (75 percent) chance that the baby will not have CF.

There is a 1-in-2 (50 percent) chance that the baby will be a carrier, like you and your partner.

Can I find out if my baby will have cystic fibrosis?
Yes, through additional testing during pregnancy. Chorionic villus sampling (CVS), generally done around the 11th week of pregnancy, is done by using a small instrument to remove a very small portion of the placenta. Amniocentesis, generally done around the 16th week of pregnancy, is performed by removing a small amount of fluid surrounding the baby using a thin needle inserted into a woman's uterus.

Are the results of these tests definite?
Yes. The results of these prenatal tests (that is, amniocentesis or CVS) are nearly 100 percent accurate about whether or not the baby will have CF.

What should I know about cystic fibrosis?
Cystic fibrosis is a life-long illness that is usually diagnosed in the first few years of life. The disorder causes problems with breathing and digestion. Cystic fibrosis does not affect intelligence.

What are the health needs of children with cystic fibrosis?
The digestive problems usually can be treated by taking medicine daily. To treat lung problems, most children with CF need to have physical therapy for about a half hour every day; this helps clear mucus from the lungs.

Do all people with cystic fibrosis have the same symptoms?
No. Some individuals have far milder symptoms than others for reasons that are not completely understood.

Might others in my family be cystic fibrosis carriers?
Yes. Even if no one in your family has had CF, other close relatives, such as brothers, sisters, aunts, uncles and cousins, also may be carriers.

What if the amniocentesis or CVS results show that the baby does not have cystic fibrosis?
If the test results indicate the baby will not have CF, you can go through the rest of your pregnancy feeling assured that the baby will not develop this condition.

What about future pregnancies?
It is important to remember that you and your partner have both been shown to be carriers of an altered CF gene. This means that in each pregnancy the two of you have together, that baby will also have a 1-in-4 (25 percent) chance of having CF.

If all tests show that the baby will have cystic fibrosis, what are my options?
Cystic fibrosis is not a curable disease. There are treatments available. However, there are no treatments available before the baby is born. Therefore, there are only two decisions that are possible once it is found out that a fetus has CF.

1. Continue the pregnancy and prepare for the addition to your family of a child with CF.
2. Terminate the pregnancy.

This excerpt from ACOG's Patient Education Pamphlet is provided for your information. It is not medical advice and should not be relied upon as a substitute for visiting your doctor. If you need medical care, have any questions, or wish to receive the full text of this Patient Education Pamphlet, please contact your obstetrician-gynecologist.