Cystic Fibrosis: Testsing and Prenatal Diagnosis

Mother holding baby with cystic fibrosis during pediatric appointment
Test for cystic fibrosis during pregnancy. Steve Debenport / Getty Images

Cystic Fibrosis (CF) is a genetic disease that causes a chronic condition that effects a person’s lungs and digestive system. A person who has cystic fibrosis carry a defective gene that causes the body to have thick mucus that can cause the lungs to be filled with fluid, which also makes lung infections more likely. In addition, it prevents natural enzymes in the body from breaking down and absorbing food.

About 30,000 people in the United States have cystic fibrosis.

About 10 million Americans are carriers of the CF gene. These people do not have symptoms of CF. Genetic testing to see if you are a carrier is fairly simple. It can be done with a blood test or by gently removing cells from the inside of your mouth. You should be tested if you have a family history of CF or if you request it. Cystic fibrosis rates vary by ethnicity with Caucasians being more likely to be carriers. If you are a known carrier or if you have a family history of CF you may wish to consider genetic counseling.

Cystic fibrosis will only occur if a baby inherits the defective gene from both parents. If both parents are carriers of the CF gene, there is:

  • a 25 % chance that the child will have CF
  • a 50% chance that the child will not have CF but will carry the gene
  • a 25% chance that the child will not have CF, nor carry the gene

    You are also able to use chorionic villus sampling (CVS) and amniocentesis to test your baby during pregnancy. While these genetic tests will not tell you the severity of the CF if your baby is diagnosed, it is nearly 100% effective in diagnosing CF.

    If you did not have genetic testing prior to conception or your baby is already born you can also have your baby tested shortly after birth.

    Many states do newborn screening anyway, though there is not one set of tests that every state does. Be sure that you talk to your baby’s practitioner to see exactly what tests are performed routinely where you live.


    Cystic Fibrosis Prenatal Screening and Diagnosis. Last accessed August 4, 2015.