Cystic Fibrosis Carrier Screening During Pregnancy

The American College of Obstetricians and Gynecologists recommends cystic fibrosis carrier screening to couples planning a pregnancy or those already pregnant to help determine if a couple is at risk of having a child with cystic fibrosis.

Cystic fibrosis screening is a personal decision based on you and your partner’s level of risk, genetic history, family situation, and your religious/spiritual beliefs. You should discuss any concerns or questions you may have about cystic fibrosis carrier screening with your obstetrician. The following information will help you better understand the condition and screening process.

What is cystic fibrosis?
Cystic fibrosis is a genetic disease that causes respiratory and digestive problems and affects one in every 3,300 people in the United States. Symptoms range from mild to severe. Those with cystic fibrosis often have chronic lung problems, such as pneumonia, which worsen over time. Cystic fibrosis also affects digestion, resulting in diarrhea and poor growth.  Treatments are available but in general, people with cystic fibrosis have a shortened lifespan. Men with cystic fibrosis are usually infertile. Cystic fibrosis does not affect intelligence.

What is the purpose of cystic fibrosis carrier screening?
Cystic fibrosis carrier screening identifies individuals who are carriers, and at risk of having a child affected with cystic fibrosis. The test requires a simple blood sample and results are usually ready within seven to 14 days.

If both partners are cystic fibrosis carriers, prenatal testing by chorionic villus sampling or amniocentesis can be performed to determine if the unborn baby has inherited the parents' abnormal cystic fibrosis genes. Testing the baby after birth is also an option if a couple does not want a prenatal diagnosis.

Will the cystic fibrosis carrier screen detect all cystic fibrosis carriers?
No. There are rare abnormalities (mutations) in the cystic fibrosis gene that the current screening test cannot detect. Negative results from cystic fibrosis carrier screening significantly lowers, but does not completely eliminate the risk of being a carrier.

Could I be a carrier?
Every person has two copies of a gene, one inherited from each parent. If a person has one normal and one abnormal cystic fibrosis gene, that person is a carrier. The chance of being a carrier of cystic fibrosis depends on your race/ethnic background (see Table). Most carriers are healthy and do not know they are carriers unless they have a screening test or an affected child.

How is cystic fibrosis inherited?
If both parents are carriers of an abnormal cystic fibrosis gene, there is a chance that each parent will pass the abnormal gene on to their child. When both partners in a couple are carriers, any child they have has a one-in-four (25 percent) chance to inherit the disease. Having two copies of the abnormal cystic fibrosis gene results in cystic fibrosis.

Is cystic fibrosis screening required?
No. The decision to accept or decline screening is entirely up to the individual or couple.

Cystic Fibrosis Carrier Rates

*Talk to your provider if your race/ethnic group is not represented.

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