Testing is a normal part of care during pregnancy to see how the baby is growing and to monitor its health. Some tests are routine, while other tests are only done when there is a special need or concern.

Your physician will consider many factors – including health history and the suspected diagnosis – when they decide which tests to order for you and your baby.

Talk with your physician to be sure that you understand what you will learn from a test and whether or not there are any risks to consider.

Ultrasound Tests

The most direct way a physician can monitor your baby’s condition during fetal life is to image the baby with ultrasound. An ultrasound test is painless and safe. The same equipment is used to see many different things in the developing fetus. Your physician may order several types of ultrasound tests during your pregnancy.

  • 20-week anatomy scan

    Women in their second trimester are routinely scheduled for a “level 2 ultrasound,” commonly called the 20-week anatomy scan. It’s a great way to see how the baby is developing and make sure that everything is progressing the way it should. This test looks at the fetal anatomy and growth, the placenta, and the amniotic fluid. Sometimes a follow-up scan is recommended if the physician cannot see everything they need to because of the fetal position or other limitations. An obstetrician or maternal fetal medicine (MFM) specialist reviews the test results.

  • fetal echocardiogram

    The fetal echocardiogram focuses on the fetal heart and blood flow. Your physician may order this test because there is a known risk for a heart problem – such as a family history of CHD – or because they either couldn’t see the heart clearly on the 20-week anatomy scan or thought they saw a problem with the heart. An MFM or pediatric cardiologist reviews the test results.

  • Growth scan

    This ultrasound to evaluate fetal growth and wellbeing can be done once or multiple times during a pregnancy depending on the clinical situation. The first fetal growth scan is typically is scheduled between 28 and 32 weeks of pregnancy. An obstetrician or MFM reviews the test results.

  • Hydrops check

    The hydrops check looks for any unusual fluid collections in the fetal body. Fluid can collect in several areas – including around the heart or lungs, in the abdomen, or in the skin. Hydrops checks are recommended when the underlying fetal condition increases the risk for collecting fluid. This test may be done once or regularly, depending on the ultrasound findings and the diagnosis. An obstetrician or MFM reviews the test results.

Non-Stress Test

A non-stress test monitors the baby’s heart rate. It is commonly done in the third trimester to check on the fetal health. During this test, the fetal heart rate is monitored to see how it responds both to periods of activity and periods of rest. The physician also watches for uterine contractions. It is called “non-stress” because nothing is done to place stress on the fetus during the test. An obstetrician or MFM reviews the test results.

Genetic Testing and CHD

It’s natural to worry about what caused your child to have CHD. In many cases, there is no clear cause. In some children the heart is the only part of their body that didn’t form normally – this is called an “isolated” abnormality. In other children, CHD occurs with other anatomic differences – this is called “syndromic” abnormality.

There is frequently a genetic component to a cardiac malformation. Genes are often referred to as the “blueprints” for the body and they come packaged in structures called chromosomes. Humans usually have 23 pairs of chromosomes. The genes in our chromosomes are responsible for telling our early embryonic cells how to grow, divide, and eventually form a human body.

Sometimes the fetal genetic information has errors that can result in a problem with the baby’s development. For example:

  • There can be an entire extra chromosome = a trisomy
  • A piece of a chromosome may be missing = a deletion
  • A section of a chromosome can have an extra copy = a duplication
  • An error within a single gene that impairs how the protein will function = a pathogenic variant  

Chromosomal and genetic testing looks for these mistakes in the genes. A common cause for isolated CHD is a combination of many factors – such as small errors in multiple genes in conjunction with unknown environmental factors (known as multifactorial inheritance).

There are two basic types of genetic tests available in pregnancy: screening tests and diagnostic tests.

Even the most thorough genetic testing may not answer what caused the heart to form abnormally. That’s because scientists don’t know what all the possible mistakes are that can cause cardiac malformations.

Screening Tests

These tests provide more specific information about the chance of a problem but carry no risk to the pregnancy.

Sequential Combined Screening

Using a sample of your blood from the first and second trimesters, a nuchal translucency measurement from the back of the fetal neck, and your age, you receive a calculated risk of Down syndrome/trisomy 21, trisomy 18, and neural tube defects.

Noninvasive Prenatal Testing

Takes a sample of your blood to look for fragments of fetal chromosomes that slip into your bloodstream from the placenta. Not all NIPT tests are the same, but it generally looks for Down syndrome, trisomy 18, trisomy 13, sex chromosome abnormalities, and triploidy (an entire third set of chromosomes).

Diagnostic Tests

Chorionic Villus Sampling or amniocentesis can diagnose a chromosomal or genetic condition in the fetus prior to birth, but both carry a slight chance of miscarriage. Your physician can tell you more about these basic types of diagnostic genetic tests if they recommend that you consider them.

Karyotype

Looks for trisomies and large rearrangements in the chromosomes.

Chromosomal Microarray (CMA)

Checks for smaller missing or extra pieces of genetic material.

Fluorescence In Situ Hybridization (FISH)

Checks to see if a specific piece of the genetic material is missing.

Congenital Heart Disease Genetic Panel

Sequences multiple different genes to look for pathogenic variants.

Whole Exome Sequencing (WES)

Sequences all coding areas of the chromosomes to look for pathogenic variants in many genes associated with CHD.

What Are the Benefits of Genetic Testing?

  • Genetic test results may help answer the question “what caused my child’s congenital heart disease?”

  • If a genetic syndrome is identified, you and your child’s physicians may look for other non-heart related health conditions that are also found in that syndrome.

  • Earlier detection can generally lead to earlier treatment of many of these conditions after the baby is born, and possibly lead to better outcomes.

  • In some cases, a prenatal genetic diagnosis can tell you information about your child’s potential for intellectual development.

  • Genetic testing may also provide a more precise estimate of the chances of having another child with CHD – the medical term for this is “recurrence risk.”

  • A genetic testing result may result in a recommendation that other family members have an echocardiogram or other cardiac assessments.

Understanding the Results of Genetic Testing

Positive Results

This finding identifies the cause of your child’s congenital heart disease and informs you of the chance for it to happen again. Other family members can be tested to see if they carry the same genetic change.

Negative Results

This means that a genetic cause of your child’s congenital heart disease was not identified. A negative result does not rule out an underlying genetic cause of your child’s CHD. As our understanding of the genetics of CHD and our genetic testing technology improves, it is possible we will be able to identify a cause in the future.

Uncertain Results

Sometimes called a “variant of unknown significance (VUS),” uncertain results indicate that a change in the genetic code was found, but there is not enough proof to know if it is a harmless change or one that caused your child’s heart disease. This inconclusive result cannot be used to determine decisions about care or identify other at-risk family members. Over time, a VUS may be reclassified as pathogenic or benign.

Meg Homeyer, Genetic Counselor

Hannah Ison, Genetic Counselor

Sharon Paige, Physician

Sameer Pangrekar, Parent

See the full list of contributors to the CHD Care Compass

Last Update: September 11, 2021

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