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Do Some Prenatal Tests Carry More Risk than Others?

by Melissa Bell
3 minutes read

If you and your partner are at an elevated risk of having a baby with a genetic condition, prenatal testing may help you gather the information you need to prepare and make decisions about your baby’s care.  It’s important to know that some prenatal tests involve more risk than others. Making an informed decision about prenatal tests and considering potential outcomes will help you make the right decision for you and your family.

Invasive vs. Noninvasive Prenatal Tests

An invasive diagnostic test is a test that requires your physician to use instrumentation to physically enter the body, whereas a noninvasive test is one in which no break in the skin is created (apart from certain blood drawing procedures).  Examples of noninvasive tests include ultrasounds and maternal blood tests, which report on the baby’s likelihood of inheriting a genetic condition. The risks of undergoing an ultrasound or a blood test are slim to none, with the main complication being slight discomfort during the test.

Beyond the standard blood tests offered to any expectant mother, prenatal genetic screening tests can help parents who may be at a higher risk for having a child with a genetic condition get a clearer picture of the baby’s likelihood of inheriting a disorder. For example, the MaterniT® 21 PLUS test is an advanced screening tool that assesses an unborn baby’s risk for Down syndrome (trisomy 21), Edwards syndrome, Patau syndrome (trisomy 13), and many other conditions.

This information can help parents make decisions about whether to move forward with invasive tests like amniocentesis, which are riskier than blood tests.  During an amniocentesis, amniotic fluid is removed from the placenta and tested for genetic conditions.  This procedure carries a small risk of miscarriage (less than 1%, or approximately 1 in 200 to 1 in 400).

Chorionic villus sampling, another common invasive test, also carries some risk of miscarriage.In this procedure, a sample of a part of the placenta called the chorionic villi is extracted, either through the vagina or through the abdominal wall.  Though there’s no general consensus on the risk of miscarriage with CVS, it’s estimated to be somewhere between 1 in 100 and 1 in 360.

Your physician will take all your risk factors into account, including the results of noninvasive tests and medical history, before advising invasive testing.

Deciding Whether to Take Prenatal Tests 

Prenatal tests can provide information about your baby’s health, and can quantify the possibility that your baby could be born with a genetic condition. The results and information gathered from these tests will allow you to make better healthcare decisions, and for you and your family to prepare for this possibility.

Though undergoing tests – and waiting for the results – can be extremely stressful, communicating with your doctor or genetic counselor can help ease tensions.


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