Blood Tests to Show Your Risk for Miscarriage

When they can help—and when they don’t

Blood tests to show your risk of miscarriage have become more common. The tests show if you have a condition called “thrombophilia.” This condition can increase blood clots. It may increase the risk of a miscarriage or other problems during pregnancy.

There are many different tests for thrombophilia. Doctors often order the tests for pregnant women who have had problems—such as miscarriage, a sharp rise in blood pressure (pre-eclampsia), or a baby that did not develop normally.

But often, tests are not needed. Even if you have had a pregnancy problem, you may not need any of these tests. Here’s why:

The test results are not always useful.

Usually, the test results do not help you and your doctor make decisions about your care.

For example, some blood tests look for certain genes. The genes can increase the risk of blood clots. But the genes do not increase your risk of miscarriage or other problems in pregnancy. Often, thrombophilia is mild and does not cause any problems. Many women who have it go on to give birth to healthy babies.

The tests can lead to unnecessary treatments and risks.

If the test shows that you have thrombophilia, your doctor may want you to take a drug called heparin during your pregnancy. This drug is injected and helps prevent blood clots.

But it is not clear that this drug lowers the risk of miscarriage or other problems. Also, the injections can cause side effects, such as heavy bleeding and allergic reactions.

The tests can be a waste of money.

The blood tests can cost $1,000 or more. Some health plans don’t pay for them. And you may also waste a lot of money on unneeded treatments. Heparin, for example, can cost hundreds of dollars, too.

Most people don’t need the tests.

You do not need to get tested just because you’ve had a miscarriage or pregnancy complication in the past. There are more effective ways to reduce your risks.

Consider a thrombophilia test if:

  • You have had a blood clot in a vein deep in the body (a deep vein thrombosis).
  • You have had a clot that traveled to a lung for no known reason (a pulmonary embolism).
  • You have had three or more miscarriages. In this case, you should consider being tested for a form of thrombophilia called “antiphospholipid syndrome.” This syndrome increases the risks of miscarriage, poor growth of the fetus, and pre-eclampsia. This syndrome can be treated with aspirin and heparin. In this case, the test and treatment have more benefits than risks.

This report is for you to use when talking with your health-care provider. It is not a substitute for medical advice and treatment. Use of this report is at your own risk.

© 2018 Consumer Reports. Developed in cooperation with the Society for Maternal-Fetal Medicine.