Should I have genetic testing for cystic fibrosis if I'm planning a pregnancy?

If you’re planning a pregnancy, you might wonder whether genetic testing for cystic fibrosis (CF) is something you should consider. Cystic fibrosis is one of the most common serious inherited conditions in white populations, and carrier screening can help you understand your risk of passing it on to your children.

What is cystic fibrosis and how is it inherited?

Cystic fibrosis is a life-shortening genetic condition that affects the lungs, digestive system, and other organs. It’s caused by changes (mutations) in a gene called CFTR. The condition follows what’s called autosomal recessive inheritance - which means a child needs to inherit a changed copy of the gene from both parents to develop cystic fibrosis.

If you’re a carrier, you have one working copy and one changed copy of the CFTR gene. Carriers don’t have cystic fibrosis themselves and are usually healthy. But if both you and your partner are carriers, there’s a 1 in 4 (25%) chance with each pregnancy that your child will have cystic fibrosis.

Cystic fibrosis is particularly common in people of northern European ancestry. The outlook for people with CF has improved considerably over recent decades, largely through earlier diagnosis, more intensive treatment, and care in specialist centres. However, it remains a serious condition requiring lifelong management.

Who might benefit from cystic fibrosis carrier screening?

Carrier screening for cystic fibrosis is typically offered to couples who are:

• Planning a pregnancy and want to understand their risk before conceiving
• Already pregnant and considering their testing options
• Related to someone with cystic fibrosis - having a family history increases your chance of being a carrier
• Of white European background - though CF occurs in all ethnic groups, it’s most common in white populations

You don’t need to have a family history to benefit from carrier screening. Many carriers have no known family connection to cystic fibrosis. Screening programmes have been developed specifically because most carriers are identified through population screening rather than family history.

What does carrier testing involve?

Carrier testing for cystic fibrosis looks for changes in the CFTR gene. There are many different mutations that can cause CF - well over a thousand have been identified worldwide, though a smaller number account for most cases. The specific mutations tested for may vary depending on which screening panel is used.

The test itself is straightforward. It typically requires either:

• A blood sample taken at a clinic or collection point
• A cheek swab (buccal swab) that you can do at home

Results usually take several weeks from when the laboratory receives your sample. Before having the test, you’ll typically have a consultation to discuss what the results might mean and help you decide whether testing is right for you.

Understanding your results

Your carrier screening results will show whether any CFTR mutations were detected:

Carrier detected: You have one changed copy of the CFTR gene. This means you’re a carrier but won’t develop cystic fibrosis yourself. If your partner is also a carrier, you’ll be offered genetic counselling to discuss the implications for your pregnancy plans.

No mutation detected: The test didn’t find any of the CFTR mutations it was looking for. This significantly reduces your chance of being a carrier, but doesn’t eliminate it completely - very rare mutations might not be included in the screening panel.

Carrier status uncertain: Occasionally, testing finds a genetic change whose significance isn’t clear. You’ll be offered specialist genetic counselling to discuss what this means.

If both you and your partner are found to be carriers, you’ll have a 1 in 4 chance of having a child with cystic fibrosis with each pregnancy. Your genetic counsellor can discuss your options, which might include:

• Prenatal diagnosis during pregnancy to see if the baby has inherited both changed copies
• Pre-implantation genetic testing if you’re considering IVF
• Preparing for the possibility of having a child with cystic fibrosis
• Reconsidering your pregnancy plans

There’s no right or wrong choice - the decision is deeply personal and depends on your individual circumstances and values.

Broader carrier screening options

Many couples planning a pregnancy choose to have broader carrier screening that includes cystic fibrosis alongside testing for other inherited conditions. This approach recognises that CF is just one of many recessive conditions, and that testing for multiple conditions at once can provide a more complete picture of your reproductive risks.

Comprehensive carrier screening panels may test for hundreds or even thousands of genes associated with inherited conditions. The advantage is that you gain information about a wider range of conditions with a single test. The complexity of interpreting results increases with the number of conditions tested, so genetic counselling becomes particularly important.

What you can do at Jeen

Jeen offers several carrier screening options that include cystic fibrosis testing:

Our Carrier Screening tests 1,008 genes for inherited recessive conditions, including CFTR. The test uses an at-home buccal swab (an in-clinic blood draw is available for an additional £40) and includes 30-minute genetic counselling to help you understand your results. Results are available within 17-21 working days of the laboratory receiving your sample, with variant interpretation aligned to NHS Genomic Medicine Service standards.

For couples wanting the most comprehensive pre-conception genetic assessment, our Carrier Screening + Karyotype bundle combines the 1,008-gene carrier panel with chromosome-level karyotype analysis. This complete work-up uses one blood draw and provides one integrated report, with 30-minute specialist genetic counselling covering both tests. The bundle saves £80 for individuals or £130 for couples compared to ordering the tests separately.

If you want even broader coverage, the CGT - Igenomix Carrier Genetic Test uses whole-exome sequencing to analyse 1,993 genes (male) or 2,057 genes (female), covering over 2,200 inherited recessive conditions. This test includes 30-minute pre-test genetic counselling, with results reviewed by your genetic counsellor within 25 working days. Blood collection is available at any of our 200+ partner collection points (£40) or via a home-nurse visit (£65).

For those already pregnant, the Unity Complete Screen offers a combined approach from 9 weeks of pregnancy. It includes an 8-condition fetal screen plus a 4-condition carrier panel (12 conditions total, including cystic fibrosis), with a free midwife consultation before you take the test and combined parental and fetal risk assessment. Results are typically available within 17-21 days.

All our carrier screening services include genetic counselling to help you understand what the results mean for you and your family. The NHS offers carrier screening in certain circumstances, particularly if you have a family history of CF or belong to a higher-risk group, but routine population screening isn’t universally available. Our panels test for a much broader range of conditions than standard NHS screening, helping you make informed decisions about your reproductive health.