Cell-free DNA (cfDNA) is a screening test that can be performed any time after 10 weeks of pregnancy that screens for common chromosome conditions (Down syndrome, trisomy 18, and trisomy 13), as well as sex chromosomes (XX and XY), which can also incidentally tell the sex of the baby.
cfDNA has also been called non-invasive prenatal screening (NIPS), non-invasive prenatal testing (NIPT), and by several brand names, such as Harmony, Panorama, MaterniT21, Verifi, and InformaSeq. cfDNA will not tell you ‘yes’ or ‘no’ about these conditions, but can tell you whether there is an increased chance for the pregnancy to have these chromosome conditions. If the results say there is an increased risk, you may be offered diagnostic tests, such as chorionic villus sampling (CVS) or amniocentesis. These diagnostic tests can provide ‘yes’ or ‘no’ answers, but come with a risk of miscarriage. Because of this, diagnostic tests are optional and are never anything someone has to do.
The conditions that are screened for can vary in severity, from little to no medical issues to severe or life-limiting health complications. Which conditions are screened for also vary from lab to lab, but most labs screen for Down syndrome, trisomy 18, trisomy 13, fetal sex, and sex chromosome differences. Most of these conditions do not run in families, but the chance of chromosome conditions, such as Down syndrome, are higher in women who will be 35 or older when the baby is born.
If a screening test, such as cfDNA, were to show an increased risk for a condition, a diagnostic test, such as amniocentesis or chorionic villus sampling (CVS), would be available to provide more definitive information. It is also important to remember that if a screening test shows a low risk, the chance the pregnancy has those conditions is reduced but not eliminated.
It is important to discuss your cfDNA results with a doctor or genetic counselor to understand what the results mean for your pregnancy, and make sure you have all of the information necessary to decide on the best next steps for you and your family.