Hi, I’m Doctor Stephanie Martin with Southern Colorado Maternal Fetal Medicine. I am a maternal fetal medicine specialist, which means that I take care of complicated pregnancies. Those complications might be due to issues with Mom’s health or with the unborn baby.
Today we’re going to talk about Cell Free Fetal DNA Screening.
That’s a lot to take in in one bite, but basically what we’re talking about is testing the unborn baby for genetic conditions before the baby is even born.
The advantage of this testing is that we can do it by taking a sample of the mom’s blood. Through that, we can extract or remove the baby’s DNA from the mom’s blood sample and tell the parents whether or not they can expect to have an increased risk for having a baby with certain genetic conditions.
Now, this testing, which is also known as Non-Invasive Prenatal Testing or “NIPT,” is commonly offered through MFM offices.
It is most accurate for babies that have trisomy 21, also known as Down Syndrome.
It can also test for conditions called trisomy 13 or 18 and can detect the gender or the sex of the baby.
It’s a very accurate test, but it is not 100%.
For Down syndrome the test is able to detect whether the baby has the condition in more than 99% of cases. However, this test is intended for women at high risk of having a baby with one of these genetic conditions.
Women at high risk include those that are over 35 years of age at the time of their due date or certain abnormal ultrasound findings.
These findings can be seen as early as the first trimester, and so we can offer testing as early as 10 weeks in the pregnancy.
Sometimes the test is unable to be performed even though we draw the mom’s blood. That might mean that there’s not enough sample of DNA in the mom’s blood.
The chances of this go up if we do the test before 10 weeks or if the mom weighs over 250 pounds.
Unfortunately, if the test result comes back as uninterpretable or not able to give a result, it does also increase the risk that the baby is abnormal.
In that setting, we might recommend repeat testing.
If the test comes back abnormal, it does not necessarily mean the baby is abnormal and your doctor will be recommending additional invasive testing, which we’ll talk about in another video and blog post.
With noninvasive prenatal testing, it is very important to remember that this test is currently only recommended for women that are at high risk for having this condition.
If women at low risk for having a baby with Down Syndrome or the other genetic conditions decide to have this test perform, the chances that the test will tell them that their baby is abnormal, when in fact the child is completely normal, are significantly increased. This means its accuracy is just not as good in low-risk women.
I hope this has been helpful in understanding noninvasive prenatal testing or cell-free fetal DNA.