Is prenatal testing right for you?

December 15, 2017 | by Jill Moran, MD
Categories: Healthy Driven Moms

Pregnant women are all too familiar with getting poked and prodded with a battery of tests. During your first prenatal visit alone, you’ll likely get a blood test, urine culture, physical exam, Pap test and possibly an ultrasound.

Prenatal tests have an important purpose. They can help you find out whether your growing baby has, or is at increased risk for, certain genetic and chromosomal conditions or birth defects. Sometimes conditions are passed from parent to child, and sometimes they happen on their own.

Some conditions prenatal tests can check for include:

  • Cystic fibrosis (CF)
  • Down syndrome
  • Sickle cell disease
  • Spinal muscular atrophy
  • Heart defects
  • Neural tube defects (spina bifida, anencephaly)
  • An abnormality in the esophagus, kidneys or abdominal wall
  • Edwards syndrome
  • Fragile X syndrome
  • Tay Sachs disease

The whole process can be nerve wracking. Before you get a prenatal test, talk to your doctor about the benefits and risks. Then, think about how you would use the results. There are advantages to knowing about your baby’s health ahead of time. It can give you time to plan for any special medical care she may need after she is born.

Throughout your pregnancy, there are two types of prenatal tests you may get:

  • Screening tests can tell you the risk that your baby will have certain disorders. These noninvasive tests don’t tell you for sure if your baby has a condition, they just offer a probability. As with any test, there is the possibility of false-positive or false-negative results.
  • Diagnostic tests tell you with certainty if your baby has or doesn’t have a specific genetic or chromosomal condition. Some diagnostic tests may have risks for your baby, which your doctor can discuss with you.

Your OB-GYN may recommend certain prenatal tests if you’re older than 35, if certain genetic conditions run in your family, or if your baby is at increased risk for birth defects or a chromosome disorder.

The American Congress of Obstetricians and Gynecologists (ACOG) says prenatal testing should be discussed as early as possible in pregnancy, ideally at the first obstetric visit, so that first trimester options are available.

Examples of prenatal tests you may get during pregnancy include:

  • Maternal blood tests. Blood tests are used throughout pregnancy to measure substances in the blood to see if your baby may be at increased risk for chromosome abnormalities, genetic disorders or birth defects.
    • Carrier screening for genetic conditions (1st trimester)
    • Cell-free fetal DNA screening (any time after 10 weeks, generally in the 1st trimester or early 2nd trimester)
    • Triple or Quad screen (2nd trimester)
  • Ultrasound. Ultrasound is used throughout pregnancy to check your baby’s growth, and for major physical defects in the brain and spine, facial features, abdomen, heart and limbs.
    • Ultrasound test for fetal nuchal translucency (NT) (1st trimester).
  • Chorionic villus sampling (CVS) (1st trimester). This diagnostic test involves taking a sample of tissue from the placenta to test it for chromosomal abnormalities and other genetic problems.
  • Amniocentesis (amnio) (2nd trimester). This is a diagnostic test to check the amniotic fluid from around your baby to see if she has a birth defect or genetic condition.
  • Group B strep (GBS) test (3rd trimester). This test checks fluid from your cervix for Group B strep, an infection you can pass to your baby during birth and requires antibiotics during labor.

Talk to your OB-GYN about which prenatal tests are right for you.

Edward-Elmhurst Health offers expert Maternal Fetal Medicine services by physicians experienced in handling the most complicated cases for expectant mothers and newborns, including rare and complex conditions. Learn more about our care for high-risk pregnancies.

Our genetic counselors can help you identify if you are at increased risk of passing genetic abnormalities on to your child, and what options you have.

Learn more about pregnancy and baby services at Edward-Elmhurst Health.

Related blogs:

Newborn screenings find and treat problems early to keep babies healthy

Prenatal intervention helps baby beat the odds

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