Prenatal Tests and What to Expect

Posted On: February 19, 2020 By Tamar Goldwaser, MD

When you’re focused on welcoming your new baby to the world, it can feel a little overwhelming keeping track of the various testing options at different stages in your pregnancy. Prenatal testing is an important part of making sure you remain informed on the health and development of your fetus so that  your child has the best possible outcome when it arrives. Prenatal tests include genetic carrier testing of the expecting parents, testing  for chromosome or genetic abnormalities of the fetus and ultrasound evaluation of the developing fetus.  Here’s what to expect from the various prenatal tests that your obstetrician will recommend during your first appointments.

What do prenatal tests do?

Prenatal tests have the goal of assessing how you and your baby are doing at different stages of pregnancy. Some tests are standard for every woman who is pregnant while others might be indicated if you’re experiencing complications or might be at risk for passing on certain conditions. In general, prenatal tests look for medical conditions that a mother might develop, birth defects in the developing fetus ,  as well as genetic or chromosomal conditions.  Some genetic conditions are inherited, or passed on from parents, and some are sporadic, or happen by chance.  You might  benefit from  the help of a genetic counselor who can make a more in-depth assessment of your family history and chances of passing on conditions. A genetic counselor can also help you understand the purpose of and differences between the various tests that are available to expecting parents.

What’s the difference between screening tests and diagnostic tests?

Prenatal tests can be either a screening test or a diagnostic test. The difference is that screening tests check if your baby is more likely than others to have a certain condition, but doesn’t confirm if the condition is present. Conversely, diagnostic tests can tell you for sure whether your baby has a specific condition. So, you may be recommended a diagnostic test by your maternal fetal medicine specialist based upon your personal history, risk factors or  your screening test results. These tests together can help you make the right plans and decisions for your baby by ensuring you have accuratet information about your baby’s health.

What tests are performed at each stage of pregnancy?

There are certain types of tests that will be appropriate for each trimester of pregnancy. Your obstetrician can recommend the right schedule for you and your baby during your early appointments.

First trimester tests

Soon after you become pregnant, you can expect a genetic screening test to check if you’re a carrier for different conditions that could be passed on. This usually requires a simple blood or saliva test. If you haven’t become pregnant yet but are planning to, you should have this test even before you conceive. Along with this important test, you can expect the following during the first three months of pregnancy:

  • Cell-free DNA testing, which checks your blood for placental  DNA to see if any chromosomal abnormalities are present.
  • Chorionic villus sampling (CVS), which checks tissue from the placenta to test for chromosome abnormalities and any genetic condition that might be specific to your situation.
  • Early ultrasound, which checks how far along your baby is developing and looks for any early signs of concern. This ultrasound also helps to establish your due date.
  • First-trimester screening, which usually includes a blood test and ultrasound to check for certain birth defects and chromosome abnormalities.

Second trimester tests

During months 4, 5, and 6, you will be offered  the following tests:

  • Maternal blood screening (quad screen), which checks for a risk of certain birth defects and chromosome abnormalites.
  • Amniocentesis (amnio), which takes a sample of fluid from around your baby to check for chromosome abnormalities and any genetic conditions that might be specific to your situation. It can also be performed later in pregnancy to check for infections or fetal lung maturity.
  • Ultrasound, which checks your baby’s developing organs and your baby’s overall growth.
  • Glucose screening, which checks to see if you have gestational diabetes.

Third trimester tests

Maternal fetal medicine specialist may recommend more tests or ultrasounds if your previous tests indicated a problem.

You can expect a group B strep test at this stage. This checks for a type of infection that you can pass to your baby during birth.  Group B strep is a bacteria that is commonly found in many healthy women and is not harmful to the mother herself.

Schedule an Appointment

Our team of award-winning maternal fetal medicine specialists can ensure you get the care you need throughout every stage of your pregnancy. To lean more about the right tests for you and your baby, contact our New York City office by calling or filling out our online form.

Carnegie Imaging for Women blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!

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