Prenatal Cell-Free DNA Screening
Reviewed
Also called: Cell-Free Fetal DNA, cffDNA, Non-Invasive Prenatal Test, NIPT, Non-Invasive Prenatal Screening, NIPS
A blood test during pregnancy that checks the baby's DNA in the mother's bloodstream to find out if the baby is more likely to have certain chromosome disorders, such as Down syndrome.
Specimen: Blood
Why this test may be ordered
- To screen for an increased risk of Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), or Patau syndrome (trisomy 13)
- To determine the baby's sex, especially if an ultrasound shows unclear genitals
- To check the baby's Rh blood type if the mother is Rh negative
Preparation and collection
You may want to speak to a genetic counselor before getting tested to understand possible results and what they might mean.
A health care professional will take a blood sample from a vein in your arm using a small needle. This usually takes less than five minutes.
There is no risk to your unborn baby and very little risk to you. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
Your results will show whether the screening indicates a higher or lower likelihood of certain chromosome disorders. A cfDNA screening cannot tell you for sure whether your baby has a disorder; your provider will need to order other tests to confirm or rule out a diagnosis.
- Screen-negative (lower-likelihood): It is unlikely that your baby has Down syndrome or another trisomy disorder. Limitation: A negative result does not guarantee the baby does not have a chromosome disorder; false negatives are possible. Next step: No further testing is typically needed, but discuss any concerns with your provider.
- Screen-positive (higher-likelihood): There is an increased risk that your baby has Down syndrome or another trisomy disorder. Limitation: A positive result does not confirm the baby is affected; false positives can occur. Confirmatory testing is required. Next step: Your provider will recommend confirmatory tests such as amniocentesis or chorionic villus sampling (CVS) to make a diagnosis.
- A cfDNA screening cannot tell you for sure whether your baby has a chromosome disorder; it only indicates risk.
- The screening is not as accurate if you are pregnant with more than one baby (twins, triplets, or more).
- False-positive and false-negative results are possible.
- Results must be interpreted by a healthcare professional; no reference intervals are provided.
What to do next
If your results are screen-positive, your provider will discuss confirmatory tests such as amniocentesis (usually done between weeks 15 and 20) or chorionic villus sampling (CVS, usually done between weeks 10 and 13). These tests have a slight risk of miscarriage. If you have questions about your results, talk to your provider and/or a genetic counselor.
- What does a screen-positive result mean for my baby and my pregnancy?
- What are the risks and benefits of confirmatory tests like amniocentesis or CVS?
- How accurate is this screening for the conditions being tested?
- Should I meet with a genetic counselor to discuss my results?
- What follow-up care or monitoring will I need based on my results?
Evidence source
U.S. National Library of Medicine: Prenatal Cell-Free DNA Screening