What’s the deal with prenatal testing?

During your pregnancy, you’re going to be poked, prodded + inserted more times than you care for. Rest assured, there’s an end game to all of this discomfort – namely your own health and that of your babe’s. Prenatal testing helps detect any problems like birth defects or genetic diseases as well as any potential issues with your pregnancy. The results will help you make the best decisions for before and after your child is born. Here’s the breakdown of what sort of testing you can expect:

Routine Prenatal Testing:

These are the totes routine tests that every woman will get at some point throughout her pregnancy:

  • HIV and sexually transmitted diseases
  • Anemia
  • Diabetes 
  • Hepatitis B
  • Preeclampsia aka a sign of high blood pressure
  • Pap Smear
  • Blood type 
  • Rh factor: 
  • Group B Strep Test: In the last month before you give birth, your doc will swab your vagina to check for this bacteria, which approximately 25% of all healthy women carry. Not to worry, if you test positive, it means you’re a carrier and chances are your baby will be totally healthy. Certain symptoms – like fever during labor, a UTI or premature labor – could signal heightened risk at delivering a baby with GBS, in which case your physician would want to give administer antibiotics at birth.
  • Ultrasound: Get the tissues ready. This magic wand uses sound waves to make pictures of your baby + your organs. You’ll have one, at a minimum, three times. You’ll have it once at the beginning to see how far along you are. Somewhere between 11-14 weeks, you’ll have one so docs can view the back of your baby’s neck. Folds or thick skin there could mean a higher risk of Down Syndrome. (They’ll also sample your blood at the same time) Then, at around 18-20 weeks to check your baby’s growth + organ development. If you’re having a more complicated pregnancy, you may get more ultrasounds + more chances to see babe! 

Genetic Testing:

Before you even get pregnant, you can test for all sorts of genetic disorders that may affect whether your child has any genetic diseases. It’s totally up whether you want to know and to what length, but your doctor will likely suggest some to make sure you have a healthy baby.

Some prenatal genetic tests are known as screening tests. They can determine whether your baby has an increased risk for certain disorders or diseases, but they can’t say for sure. Other diagnostic tests are more definitive. Usually screenings come first and diagnostics later. Your doc might start out with a very basic carrier test of diseases like cystic fibrosis, Tay-Sachs, sickle cell disease, and others. If both of you carry the gene for one of these diseases in your DNA, you could pass it on to your baby, even if you don’t have the disease itself. 

There are more than a few different tests to measure genetic issues. Integrated Screening takes the results of your 12 week ultrasound and bloodwork  and takes a follow up blood sample at 16-18 weeks. The results measure risk for Down Syndrome and Spinda Bifida. A sequential screen is similar to integrated screening, but your doctor reviews the results with you right after the first phase at 11-14 weeks. It’s not as accurate as the longer test, but it lets you know your baby’s risk earlier. A Triple or quadruple screening test is when your medical provider might check your blood for hormones and proteins that come from your baby or your placenta. The test measures three or four different substances to note whether your baby has a higher chance of having a birth defect or a genetic disease. This test happens in the second trimester, usually at 15 to 20 weeks.

Cell-free fetal DNA testing. Doctors use this test to find your baby’s DNA in your blood and check it for Down syndrome and two other genetic conditions, trisomy 18 and trisomy 13. You can have this done after 10 weeks of your pregnancy. Doctors don’t recommend it for every woman, usually only those who have a high-risk pregnancy. It’s not available everywhere, and some health insurance policies don’t cover it. Talk to your doctor about whether you need this test.

ALL The Other Tests

If you get a positive result on a screening, your doctor can use other tests to look for a problem.

Amniocentesis. Using a thin needle in your belly, your doctor will take a sample of the fluid that surrounds your baby and check it for genetic disorders or birth defects. The procedure does carry some risk. About 1 in 300 to 500 women will miscarry because of amniocentesis. Your doctor can tell you if it’s important for you to have this.

Chorionic villus sampling (CVS). Doctors take a small piece of your placenta by putting a needle through your belly or a small tube up your vagina. They test the sample for Down syndrome and other genetic conditions. Only some high-risk women will need this test, usually if a screening found a risk of a birth defect. The procedure will tell you for sure if there’s a problem, but it also comes with a risk of miscarriage that’s similar to amniocentesis. Talk to your doctor about whether you should have CVS.

Just remember, while all of these prenatal tests can help you make important decisions about you and your babe. it’s important to note that NO test is 100% accurate. 

Talk to your doctor about your results and what they mean. A genetics counselor can also help you decide what to do after a positive result and what that can look like for you and your family.