Pregnancy brings with it a battery of tests – not just those that your doctor requests. Sleep disturbances, food cravings, and fatigue may make some of us want to put a “pause” on pregnancy!
One of the many tests your doctor will recommend is baby’s first “up close and personal” – a screening test to make sure baby’s chromosomes (translation – what holds genetic material) and anatomy is a-ok. #babysfirstselfie.
We talked a bit about screening versus diagnostic testing and invasive versus non-invasive tests in our “Gone Shopping” post (LINK). As a refresher, the goal of this screening test is to identify moms with babies who may be at higher risk than normal for certain abnormalities. But, remember, like using an Instagram filter, a screening test doesn’t give us the clearest picture. If your screening test indicates you may be at higher risk for something fishy, your doctor will recommend a definitive test to make the picture crystal clear. Screening tests are “non-invasive” in doctor-speak, meaning a simple blood draw or ultrasound is usually all you need!
As if there aren’t enough decisions to make in pregnancy, there is a laundry list of different methods to screen for chromosomal abnormalities. Your doctor will talk to you about the pros and cons of each and what he or she usually does or recommends.
To prep for that visit, we’ll break it down for you. Let’s start at the very beginning – a very good place to start!
DOES THE EARLY BIRD GET THE WORM? FIRST TRIMESTER SCREENING:
If you want to start the screening early (think 10–13 weeks), you may get a special ultrasound, called a nuchal translucency, and a blood test to look at two markers.
The pros of the method are that you get risk assessment early. The cons are that sonographers must be certified in nuchal translucency scans, and this isn’t the best test to assess the risk of certain structural anomalies, like spina bifida.
GIMME SOME LEG POWER – THE QUAD SCREEN:
The quadruple (a.k.a. “quad”) screen is a blood test done in the second trimester. The combination of these four blood markers assesses the possibility of both chromosomal and certain structural problems.
To be clear, by “structural,” we mean things like spina bifida or other abnormalities affecting the spine. This is assessed with one of the blood tests available (called AFP), but will also be checked for during your anatomy scan, which happens around 20 weeks.
STEP BY STEP – USING THE BEST OF BOTH WORLDS:
By using a combination of blood tests in the first and second trimester along with an ultrasound (in some cases), you can get an assessment of your risk for both chromosomal abnormalities and structural problems. This approach is a bit better at detecting problems, but you have to wait until a little bit later in pregnancy to know.
There are a few ways of using this step-by-step approach – integrated, stepwise, and sequential. Your doctor will help guide you on this decision if you choose this method.
THE NEW KID ON THE BLOCK – CELL-FREE DNA:
Cell-free DNA is the most accurate “cell-fi” available (see what we did there?).
This test looks for DNA from the baby’s placenta (the organ your body grows to feed the baby!). Since it will be different (hey – 50% of baby’s DNA comes from someone else!), the test looks for the baby’s DNA and makes sure the chromosome numbers are correct.
While this NKOB is pretty cool, here are a few caveats to consider:
- The strong suit of this test is picking out those at high risk for three of the most common chromosomal abnormalities – Trisomy 21 (a.k.a. Down Syndrome), Trisomy 18, and Trisomy 13.
- This test has been most studied in women at high risk of abnormalities, like moms over the age of 35. So, if you’re not one of those high-risk individuals, you may have a higher chance at a false positive, meaning the test might detect a problem when there is none.
- This test will not assess risks for certain structural defects, like spina bifida.
GREY’S ANATOMY [SCAN]:
Last but not least, your doctor will likely recommend a detailed ultrasound to look at the baby’s anatomy somewhere around 20 weeks. This is considered a part of your prenatal care checklist that is separate from the above blood tests, but we felt it was worth a brief mention!
This bird’s eye view (we just scratched the surface of each test!) of general screening for the baby should hopefully give you a primer for when it’s time to decide what is #truly best for you and baby. And, remember, you’ll have your best supporting actor or actress (your doctor!) guiding you through this process.