Prenatal testing, including screening and diagnostic tests, can provide valuable information about your baby’s health. Understand the risks and benefits.
Types of prenatal testing
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 a baby’s neck (nuchal translucency). In Down syndrome and in certain other conditions, the nuchal translucency measurement is abnormally large.
• Second trimester screening tests. During your second trimester, your health care provider will offer another blood test called the quad screen. This test measures levels of four substances in your blood. Results indicate your risk of carrying 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 foetal DNA in the maternal bloodstream to screen for the increased chance for specific chromosome problems, such as Down syndrome. This screening can also provide information about a baby’s sex and rhesus (Rh) blood type.
Questions to consider
Prenatal screening tests for foetal abnormalities are optional. It’s important to make an informed decision about prenatal testing, especially if you’re screening for foetal conditions that can’t be treated. Before going forward, consider these questions:
• What will you do with the test results? Normal results can ease your anxiety. However, if prenatal testing indicates that your baby might have a birth defect, you could be faced with wrenching decisions — such as whether to continue the pregnancy. On the other hand, you might welcome the opportunity to plan for your baby’s care in advance.
• Will the information shape your prenatal care? Some prenatal tests detect 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 isn’t 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 pursue prenatal testing is up to you. If you’re concerned about prenatal testing, discuss the risks and benefits with your health care provider. You might also meet with a genetic counsellor for help choosing a test and understanding the results.
Taking the time to evaluate your options will help you make the best decision for you and your baby.