Prenatal Testing: Is It Right For You?

Prenatal tests, including screening and diagnostic tests, can provide valuable information about your baby’s health. Understand the risks and benefits.

By Mayo Clinic staff

Pregnancy is a time of great anticipation and sometimes anxiety. You may be worried that your baby is having health problems. While most babies are born healthy, it’s important to understand your options for details about your baby’s health.

Types of prenatal tests

The two main types of prenatal tests are:

  • screening tests. Prenatal screening tests can identify whether your baby is more or less likely to have certain birth defects, many of which are genetic disorders. These tests include blood tests, a specific type of ultrasound, and prenatal cell-free DNA testing. Prenatal screening tests are usually offered during the first or second trimester. Screening tests cannot make a definitive diagnosis. If the results indicate an increased risk for a genetic disorder, your health care provider will discuss your options for diagnostic testing to confirm the diagnosis.
  • Diagnostic tests. If a screening test indicates a possible problem, or if your age, family history, or medical history put you at higher risk of having a baby with a genetic problem, you might consider an invasive prenatal diagnostic test. A diagnostic test is the only way to be sure of a diagnosis. Some diagnostic tests, such as chorionic villus sampling and amniocentesis, carry a slight risk of miscarriage.

Types of screening tests

Prenatal screening tests include:

  • First trimester screening tests. During your first trimester, your health care provider will offer a blood test and an ultrasound to measure the size of the clear space in the tissue at the back of your baby’s neck (nuchal translucency). In Down syndrome and certain other conditions, the nuchal translucency measurement is larger than usual.
  • Second trimester screening tests. During your second trimester, your health care provider will offer you another blood test called a quad screen. This test measures the levels of four substances in the blood. The results indicate your risk of having a baby who has certain chromosomal conditions, such as Down syndrome. The test can also help detect neural tube defects, serious abnormalities of the brain or spinal cord.
  • Prenatal cell-free DNA screening. This blood test examines fetal DNA in the maternal bloodstream to detect a higher chance of specific chromosomal problems, such as Down syndrome. This test can also provide information about the baby’s gender and Rh blood type.

Questions to consider

Prenatal screening tests for fetal abnormalities are optional. It is important to make an informed decision about prenatal testing, especially if you are evaluating fetal conditions that cannot be treated. Before moving on, consider these questions:

  • What will you do with the test results? Test results within the standard range can ease your anxiety. However, if prenatal tests indicate that her baby might have a birth defect, she may have to make difficult decisions, such as continuing the pregnancy. On the other hand, you might welcome the opportunity to plan ahead for your baby’s care.
  • Will the information shape your prenatal care? Some prenatal tests find problems that can be treated during pregnancy. In other cases, prenatal testing alerts your health care provider to a condition that requires immediate treatment after birth.
  • How accurate are the results? Prenatal screening is not perfect. The rate of inaccurate results, known as false negative or false positive results, varies from test to test.
  • What are the risks? Weigh the risks of specific prenatal tests, such as anxiety, pain, or possible miscarriage, against the value of knowing the results.

The decision to have prenatal tests is up to you. If you are concerned about prenatal testing, discuss the risks and benefits with your health care provider. You can also meet with a genetic counselor to help you choose a test and understand the results.

Taking the time to review your options will help you make the best decision for you and your baby.

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