Many health concerns present at birth are due to genetic conditions. Genetic conditions are caused by changes in genes or threadlike pieces of DNA called chromosomes. The two main types of testing for genetic conditions during pregnancy are:

• Screening tests. Prenatal screening tests can find out whether your baby is more or less likely to have certain genetic conditions. Most often, these screening tests are offered during the first or second trimester of pregnancy. They include blood tests and ultrasound. Irregular results on a screening test don't mean that your baby has a genetic condition. Your healthcare professional can help you decide whether you should get diagnostic tests to find out for sure.
• Diagnostic tests. These tests are the only way to know whether your baby has a genetic condition. You can get a diagnostic test if a screening test finds that your baby has a higher risk of a genetic condition. Or you could think about getting a diagnostic test if your age, family history or health history raises your baby's risk of a genetic condition. Some diagnostic tests carry a slight risk of miscarriage. These tests include chorionic villus sampling and amniocentesis.

Prenatal tests for genetic conditions are optional. It's important to make an informed decision about testing. That's especially important if you get tested for rare conditions that don't yet have treatments.

Before you go forward with testing, ask yourself these questions:

• What will you do with the test results? Test results within the standard range may ease your worry. But if prenatal testing suggests that your baby might have a genetic condition, you could be faced with certain decisions. For example, you might have to think about whether to continue the pregnancy. Or you might welcome the chance to plan for your baby's care in advance.
• Will the information shape your prenatal care? Some prenatal tests find health conditions that can be treated during pregnancy. Other times, prenatal testing alerts your healthcare professional to a condition that needs treatment right after birth.
• How accurate are the results? Prenatal screening tests aren't perfect. The rate of wrong results varies from test to test. You can ask your healthcare professional for information about these rates. There are different kinds of wrong results. A test result called a false-positive shows a health risk when there really isn't one. A result called a false-negative shows no health risk when there really is one.
• What are the risks? Weigh the pros and cons of each test with your healthcare professional. For example, some tests may raise the risk of anxiety, pain or a miscarriage. Think about whether those risks are worth the value of getting answers from the tests.

The choice of whether to get prenatal testing for genetic conditions is up to you. If you're concerned about testing, talk with your healthcare professional about the risks and benefits. You also may meet with a genetic counselor. This healthcare professional can help you choose a test and understand the results.

Taking the time to think about your options can help you make the best decision for you and your baby.

Pregnancy is a time of great anticipation — and, sometimes, anxiety. You might worry that your baby will have health problems. While most babies are born healthy, it's important to understand your options for obtaining details about your baby's health.

The two main types of prenatal testing 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 screening. Prenatal screening tests are usually offered during the first or second trimester. Screening tests can't make a definitive diagnosis. If results indicate an increased risk for a genetic disorder, your health care provider will discuss your options for a diagnostic test to confirm the diagnosis.
• Diagnostic tests. If a screening test indicates a possible problem — or your age, family history or medical history puts you at increased 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.

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 larger than usual.
• 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 fetal 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 Rh blood type.

Prenatal screening tests for fetal abnormalities are optional. It's important to make an informed decision about prenatal testing, especially if you're screening for fetal conditions that can't be treated. Before going forward, consider these questions:

• What will you do with the test results? Test results within the standard range 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 counselor 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.