Fetal DNA Testing

New tests screen fetal DNA collected from a mother's blood

Non-invasive prenatal screening methods that test fetal DNA from a sample of the mother's blood are now available.

Fetal DNA Testing Options at OHSU

These tests are now available for some OHSU patients. Please read the FAQ below and talk to your care provider to learn more.

Fetal DNA Testing FAQ

What’s new?

Testing for some of the more common chromosome abnormalities is now available by taking a sample of mother’s blood and looking for fetal DNA (genetic material) from your baby. These tests are often called “Non-Invasive Prenatal Testing (NIPT)” or “Fetal DNA testing.”

What are these tests for?

These tests can tell us the chance, or likelihood, that a baby has certain types of chromosome abnormalities including Down syndrome, trisomy 18 and trisomy 13.

How accurate are these tests?

The accuracy of these new tests appears to be higher than other blood tests currently offered and can be performed any time in pregnancy after 10 weeks. However, these tests are not 100% accurate. They cannot screen for all known chromosome disorders. The results are not as accurate as CVS or amniocentesis.

What do the results mean?

Results generally take 1-2 weeks. A negative results means there is a very low chance a baby has Down syndrome, trisomy 18 or trisomy 13. A positive result means there is a very high chance the baby has Down syndrome, trisomy 18 or trisomy 13. In most cases, a positive result is confirmed with definative testing, such as amniocentesis. About 5% of women that do this test will not get results and may need to have their blood redrawn or will be offered further testing.

Who are the tests for?

These blood tests are currently available for women with high risk pregnancies. This includes women over 35, those with abnormal ultrasound findings, abnormal blood tests or a previous pregnancy with a chromosome abnormality.

Who performs these tests?

Three commercial laboratories currently offer these tests; Sequenom (MaterniT21plus™), Verinata Health (Verifi™ prenatal test), and Ariosa (Harmony™ prenatal test). There may be some out-of-pocket cost for these tests because not all insurance companies cover the cost.

What if I have more questions?

These tests are still very new. Testing options and results are complicated. If you are considering testing or have results to review, you may benefit from meeting with a prenatal genetic counselor. Genetic counselors are trained medical providers who can discuss the pros and cons of screening, help you understand testing results, and support you in your decision-making.