Non-invasive prenatal diagnosis
Who gets the test?
Non-invasive prenatal
diagnosis is a new type of genetic test that detects birth defects and
hereditary diseases. Many experts believe that it will one day become the
standard test, replacing other riskier screening tests.
What the test does
Until a few years ago, the
only way to test your baby's DNA was to take a direct sample of your baby's
amniotic fluid, blood, or placental tissue. You will need an amniocentesis or
chorionic villus sampling. Both have a low risk of miscarriage or
complications.
Non-invasive prenatal
diagnosis takes a different approach. It tests a small amount of your baby's
DNA that is naturally found in your own blood. Non-invasive prenatal diagnosis
can test it for birth defects such as Down's syndrome, trisomies 13 and 18, as
well as hereditary diseases such as cystic fibrosis, hemophilia, and other
conditions. It can also tell if your child is a boy or a girl.
Non-invasive prenatal
diagnosis is much more accurate than similar nuchal lumen screening tests, such
as a blood test during first trimester screening or a quad test. Because the
results seem so accurate, the test can save many women from invasive procedures
such as amniocentesis or chorionic villus sampling.
How the test works
Non-invasive prenatal
diagnosis is a simple blood test. There is no risk to you or your child. The
technician will take a small sample of blood from your arm.
What you need to know about test results
If your non-invasive prenatal
diagnosis is negative, your baby is at low risk for these birth defects. If the
result is positive, the doctor may recommend further testing. These may include
ultrasound, chorionic villus sampling, or amniocentesis.
How often is a test done during pregnancy?
Once, between 10 and 22 weeks of gestation, but this is possible anytime after 9 weeks depending on the laboratory. The test is available to all women, but is usually covered by insurance for women aged 35 and over and women at high risk of genetic abnormalities.