Prenatal Blood Tests – What to Expect

Navigating through the many different pre-natal blood tests can be confusing. Names like Sequential Screening, NIPT, and Carrier Screening meant nothing to me before being pregnant. As my doctor explained the different blood tests, I found myself being even more confused. I just wanted to know which blood test was the best option for my baby and me.

As you enter your second trimester and prepare to take multiple blood tests, it’s best to do your research beforehand. This way you’ll know what to expect and won’t be overwhelmed by the different options.

Here is a breakdown of the different blood tests:

Sequential Screening

The standard blood test that every pregnant woman takes at their 10-12 week doctor’s appointment is called “Sequential Screening”.

This test screens your baby for neural tube defects and genetic abnormalities. Examples of these defects include spina bifida and anencephaly, when the brain and skull doesn’t properly form.1 This test also screens for chromosomal abnormalities such as Down Syndrome and Trisomy 18 (this is a condition that causes developmental delays).

Again, this test is the standard test that most likely all of your pregnant friends took and is the most common to take. 

*It is recommended to check with your insurance, but this is a standard blood test and should be covered.

Non Invasive Prenatal Testing (NIPT)

I like to consider this the VIP version of the Sequential Screening. A mother would choose this test OR the Sequential Screening (you wouldn’t do both).

Essentially this test is the same. The process is the same and it tests for the same genetic abnormalities. However, the accuracy of this test is very high at 97-99 percent.

In the past, NIPTs were only recommended for women at high risk but now doctors give families the option of opting for the NIPT even if they aren’t.

The results of an NIPT screening can more accurately help you and your doctor determine whether or not diagnostic tests like chorionic villus sampling (CVS) or amniocentesis (“amnio”) should be done.

*It is recommended to check with your insurance since this test may be an out of pocket expense.

Villus Aampling (CVS) or Amniocentesis (“Amnio”)

Regardless of which blood test you chose to take, if any “red flags” pop up from it, a CVS or Amnio may be recommended. These genetic tests analyze a baby’s own genetic material, collected from the amniotic fluid or placenta, to tell with 100 percent certainty whether a baby has a chromosome abnormality.2

Please note these tests are different than the previous blood tests. This is an invasive procedure, which means they slightly increase the chance of miscarriage. This procedure is only done if recommended by your doctor or if there is indication of an abnormality from one of the previous blood tests. This is optional and you can elect not to have it done.

Carrier Screening

Previously this test was only available to families undergoing IVF. Recently it has become a standard practice for parents who conceived naturally to elect to have this test done as well. The procedure is simple – BOTH parents get their blood drawn and sent to the lab (just like the Sequential Screening and NIPT test).

This is genetic testing that is determined by your ethnic background and family history. Most genetic diseases are known as “recessive disorders,” which means that each parent needs to pass along an affected gene to the baby in order for the child to be affected. In other words, if you screen positive for a genetic abnormality but your partner does not, your child will not inherit the condition.3

For example, thalassemia runs on my husband’s side of the family, which is a blood disorder common to people of Mediterranean descent. This disease causes anemia, bone growth issues and liver problems; and in severe cases, some babies born with the condition may not survive. It was important to both my husband and I to get the Carrier Screening and when we did, we found that both of us were not carriers of the thalassemia gene. Therefore, our baby has zero percent chance of getting it. This was a big relief and something I didn’t have to worry about for 9 + months.

If both parents screen positive, there’s a 25 percent chance the baby will have the disease.

Some families choose to get this testing done before conceiving. Therefore, if both parents screen positive they may consider an egg or sperm donor, or adoption instead. Other families who are already pregnant can use this information with guidance from their doctor to choose the best route moving forward in the pregnancy.

*In the past, this test was considered elective and not covered by insurance. Most recently this test has become a standard practice and should be covered by your insurance. It is recommended to check with your insurance beforehand since insurance carriers may have different policies.

As your body is changing, and your baby is growing, the last thing you need is to be overwhelmed by the different blood test options. Navigating through them can be confusing but this breakdown is meant to make it easier to understand, giving you all the information you need to make the best decision for you and your baby.


Sources:

  1. https://www.healthline.com/health/pregnancy/sequential-screening#intro1
  2. https://www.whattoexpect.com/pregnancy/pregnancy-health/noninvasive-prenatal-testing/
  3. http://nfwh.nm.org/genetic-screening-and-testing-during-pregnancy.html